{"id":"CVE-2026-65838","aliases":["EUVD-2026-78059","GHSA-8qqm-fp2q-v734","GO-2026-6019"],"status":"published","title":"Skipper: an oversized declared-`Content-Length` body still hands OPA an empty `parsed_body`, so deny-on-presence Rego policies fail OPEN while the full payload reaches upstream","description":"Skipper is an HTTP router and reverse proxy for service composition. Prior to 0.27.35, the opaAuthorizeRequestWithBody filter in filters/openpolicyagent/openpolicyagent.go can allow an oversized declared Content-Length request to bypass a deny-on-presence Rego policy because ExtractHttpBodyOptionally leaves OPA with an empty parsed_body while forwarding the complete request body upstream. This incomplete remediation of CVE-2026-50197 affects deployments that authorize request-body content and exceed -open-policy-agent-max-request-body-size, which defaults to 1 MB. Policy logic that does not reject input.attributes.request.http.truncated_body can therefore fail open and permit a forbidden payload to reach the protected service, while small bodies and the previously fixed chunked-body case are evaluated normally. This issue is fixed in version 0.27.35.","severity":{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00464,"percentile":0.4064,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-444","CWE-754"],"published":"2026-07-17T21:49:48Z","modified":"2026-10-28T02:30:43Z","fixes":[{"ecosystem":"Go","package":"github.com/zalando/skipper","fixed_in":["0.27.26"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Go","package":"github.com/zalando/skipper","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.27.26"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/zalando/skipper","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.27.26"}]}]},{"source":"osv","ecosystem":"Go","package":"github.com/zalando/skipper","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.27.26"}]}]}],"products":[{"vendor":"zalando","product":"skipper"}],"references":[{"url":"https://github.com/zalando/skipper/security/advisories/GHSA-8qqm-fp2q-v734","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/zalando/skipper/commit/2cfceabaa6ff0af65b312dcb9bcbe84691b9d507","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/zalando/skipper/releases/tag/v0.27.35","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/zalando/skipper/releases/tag/v0.27.26","tags":["web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-65838","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-8qqm-fp2q-v734"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/65xxx/CVE-2026-65838.json","tags":["advisory"]},{"url":"https://github.com/zalando/skipper","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-65838","title":"Skipper: an oversized declared-`Content-Length` body still hands OPA an empty `parsed_body`, so deny-on-presence Rego policies fail OPEN while the full payload reaches upstream","description":"Skipper is an HTTP router and reverse proxy for service composition. Prior to 0.27.35, the opaAuthorizeRequestWithBody filter in filters/openpolicyagent/openpolicyagent.go can allow an oversized declared Content-Length request to bypass a deny-on-presence Rego policy because ExtractHttpBodyOptionally leaves OPA with an empty parsed_body while forwarding the complete request body upstream. This incomplete remediation of CVE-2026-50197 affects deployments that authorize request-body content and exceed -open-policy-agent-max-request-body-size, which defaults to 1 MB. Policy logic that does not reject input.attributes.request.http.truncated_body can therefore fail open and permit a forbidden payload to reach the protected service, while small bodies and the previously fixed chunked-body case are evaluated normally. This issue is fixed in version 0.27.35.","status":"published","published":"2026-09-14T20:01:27.862Z","modified":"2026-09-15T13:55:41.273Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-754"],"updated_at":"2026-11-02T13:37:02.780526Z"}],"euvd":[{"id":"EUVD-2026-78059","description":"Skipper is an HTTP router and reverse proxy for service composition. Prior to 0.27.35, the opaAuthorizeRequestWithBody filter in filters/openpolicyagent/openpolicyagent.go can allow an oversized declared Content-Length request to bypass a deny-on-presence Rego policy because ExtractHttpBodyOptionally leaves OPA with an empty parsed_body while forwarding the complete request body upstream. This incomplete remediation of CVE-2026-50197 affects deployments that authorize request-body content and exceed -open-policy-agent-max-request-body-size, which defaults to 1 MB. Policy logic that does not reject input.attributes.request.http.truncated_body can therefore fail open and permit a forbidden payload to reach the protected service, while small bodies and the previously fixed chunked-body case are evaluated normally. This issue is fixed in version 0.27.35.","status":"published","published":"2026-09-14T20:01:27Z","modified":"2026-09-15T13:55:41Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high"}],"updated_at":"2026-11-02T17:28:18.438671Z"}],"ghsa":[{"id":"GHSA-8qqm-fp2q-v734","title":"Skipper: Incomplete fix for CVE-2026-50197: an oversized body can bypass OPA deny-on-presence Rego policies","description":"### Summary\n\nA wrong policy can be an open door. \nYou have to check `input.attributes.request.http.truncated_body` in your policy.\n\n### Description\n\nIncomplete fix for CVE-2026-50197: an oversized declared-`Content-Length` body still hands OPA an empty `parsed_body`, so deny-on-presence Rego policies fail OPEN while the full payload reaches upstream.\n\nThe CVE-2026-50197 fix (commit `3152f3b0`, PR #4041, v0.26.10) substituted `expectedSize = maxBodyBytes`\nonly when `req.ContentLength \u003c 0` (chunked / HTTP/2 without content-length). But when a request declares a\n`Content-Length` larger than `maxBodyBytes`, `expectedSize \u003e maxBodyBytes`, the body-extraction `if` is\nskipped entirely, and `ExtractHttpBodyOptionally` returns `rawBodyBytes = nil` — so OPA evaluates an empty\n`parsed_body`, while the full forbidden payload still flows to the upstream. A deny-on-presence policy\n(`default allow = true; allow = false if input.parsed_body.\u003cforbidden\u003e`) — the exact Rego shape the\nadvisory describes — fails OPEN. The fix's own comment reasons only about `ContentLength == -1`; the\noversized branch was never considered, and the added PoC test only covers small bodies.\n\n### Affected code\n\n- `filters/openpolicyagent/openpolicyagent.go` `ExtractHttpBodyOptionally`: the\n  `expectedSize \u003c= maxBodyBytes` gate lets an oversized declared body fall through to\n  `return req.Body, nil, func() {}, nil` (OPA sees an empty document).\n- Corroborated by Skipper's own unit test \"Read body exhausting max bytes\" (`{ \"welcome\": \"world\" }`,\n  `maxBodySize: 5` → `bodyInPolicy: \"\"`).\n\n### Steps to reproduce\n\nSee attached `docker-compose.yml` (official `golang` image) + `setup.sh` + `exploit.sh`, which run a real\nSkipper proxy (`proxytest`) with a real OPA control plane (`opasdktest`),\n`WithMaxRequestBodyBytes(32)`, policy `allow = false if input.parsed_body.action == \"delete\"`, route\n`* -\u003e opaAuthorizeRequestWithBody(\"test\") -\u003e upstream`:\n- `{\"action\":\"delete\"}` (19B ≤ 32) → **403** (denied).\n- `{\"action\":\"delete\",\"pad\":\"X..64\"}` (\u003e 32) → **200**, upstream received the full body (BYPASS).\n- small chunked `{\"action\":\"delete\"}` → **403** (positive control: the original CVE is fixed).\n\n(Library-tier: validated via Skipper's real proxy test harness, not a deploy of the official image; benign\noracle = status diff + upstream-received body; no RCE.)\n\n### Impact\n\nDeployments authorizing on request-body content via `opaAuthorizeRequestWithBody` + deny-on-presence Rego\ncan be bypassed by inflating the request body past `-open-policy-agent-max-request-body-size` (default\n1 MB); the full payload still reaches the upstream.\n\n### Mitigation\n\nDocument how policy owners should block requests with oversized body.\n\nExample deny by default and use \"allow if\" no oversized body:\n```rego\ndefault allow := false\n\nallow if {\n    input.attributes.request.http.truncated_body == false\n    # ... body-based conditions\n}\n```\n\nExample allow by default and use \"deny if\" an oversized body:\n```rego\ndefault deny := false\n\ndeny if {\n    input.attributes.request.http.truncated_body == true\n    # ... body-based conditions\n}\n```\n\nDocumentation is published by https://github.com/zalando/skipper/releases/tag/v0.27.26\n\n### Credit\n\nReported as part of an incomplete-patch measurement study (responsible disclosure).","status":"published","published":"2026-07-17T21:49:48Z","modified":"2026-09-25T17:03:33Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high"}],"cwes":["CWE-444"],"updated_at":"2026-11-02T14:41:21.616682Z"}],"nvd":[{"id":"CVE-2026-65838","description":"Skipper is an HTTP router and reverse proxy for service composition. Prior to 0.27.35, the opaAuthorizeRequestWithBody filter in filters/openpolicyagent/openpolicyagent.go can allow an oversized declared Content-Length request to bypass a deny-on-presence Rego policy because ExtractHttpBodyOptionally leaves OPA with an empty parsed_body while forwarding the complete request body upstream. This incomplete remediation of CVE-2026-50197 affects deployments that authorize request-body content and exceed -open-policy-agent-max-request-body-size, which defaults to 1 MB. Policy logic that does not reject input.attributes.request.http.truncated_body can therefore fail open and permit a forbidden payload to reach the protected service, while small bodies and the previously fixed chunked-body case are evaluated normally. This issue is fixed in version 0.27.35.","status":"published","published":"2026-09-14T20:16:49.103Z","modified":"2026-09-16T13:42:48.383Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-754"],"updated_at":"2026-11-02T14:12:47.335523Z"}],"osv":[{"id":"CVE-2026-65838","title":"Skipper: an oversized declared-`Content-Length` body still hands OPA an empty `parsed_body`, so deny-on-presence Rego policies fail OPEN while the full payload reaches upstream","description":"Skipper is an HTTP router and reverse proxy for service composition. Prior to 0.27.35, the opaAuthorizeRequestWithBody filter in filters/openpolicyagent/openpolicyagent.go can allow an oversized declared Content-Length request to bypass a deny-on-presence Rego policy because ExtractHttpBodyOptionally leaves OPA with an empty parsed_body while forwarding the complete request body upstream. This incomplete remediation of CVE-2026-50197 affects deployments that authorize request-body content and exceed -open-policy-agent-max-request-body-size, which defaults to 1 MB. Policy logic that does not reject input.attributes.request.http.truncated_body can therefore fail open and permit a forbidden payload to reach the protected service, while small bodies and the previously fixed chunked-body case are evaluated normally. This issue is fixed in version 0.27.35.","status":"published","published":"2026-09-14T20:01:27.862Z","modified":"2026-10-28T02:30:43.801688185Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high"}],"cwes":["CWE-754"],"updated_at":"2026-11-02T15:45:14.46177Z"},{"id":"GHSA-8qqm-fp2q-v734","title":"Skipper: Incomplete fix for CVE-2026-50197: an oversized body can bypass OPA deny-on-presence Rego policies","description":"### Summary\n\nA wrong policy can be an open door. \nYou have to check `input.attributes.request.http.truncated_body` in your policy.\n\n### Description\n\nIncomplete fix for CVE-2026-50197: an oversized declared-`Content-Length` body still hands OPA an empty `parsed_body`, so deny-on-presence Rego policies fail OPEN while the full payload reaches upstream.\n\nThe CVE-2026-50197 fix (commit `3152f3b0`, PR #4041, v0.26.10) substituted `expectedSize = maxBodyBytes`\nonly when `req.ContentLength \u003c 0` (chunked / HTTP/2 without content-length). But when a request declares a\n`Content-Length` larger than `maxBodyBytes`, `expectedSize \u003e maxBodyBytes`, the body-extraction `if` is\nskipped entirely, and `ExtractHttpBodyOptionally` returns `rawBodyBytes = nil` — so OPA evaluates an empty\n`parsed_body`, while the full forbidden payload still flows to the upstream. A deny-on-presence policy\n(`default allow = true; allow = false if input.parsed_body.\u003cforbidden\u003e`) — the exact Rego shape the\nadvisory describes — fails OPEN. The fix's own comment reasons only about `ContentLength == -1`; the\noversized branch was never considered, and the added PoC test only covers small bodies.\n\n### Affected code\n\n- `filters/openpolicyagent/openpolicyagent.go` `ExtractHttpBodyOptionally`: the\n  `expectedSize \u003c= maxBodyBytes` gate lets an oversized declared body fall through to\n  `return req.Body, nil, func() {}, nil` (OPA sees an empty document).\n- Corroborated by Skipper's own unit test \"Read body exhausting max bytes\" (`{ \"welcome\": \"world\" }`,\n  `maxBodySize: 5` → `bodyInPolicy: \"\"`).\n\n### Steps to reproduce\n\nSee attached `docker-compose.yml` (official `golang` image) + `setup.sh` + `exploit.sh`, which run a real\nSkipper proxy (`proxytest`) with a real OPA control plane (`opasdktest`),\n`WithMaxRequestBodyBytes(32)`, policy `allow = false if input.parsed_body.action == \"delete\"`, route\n`* -\u003e opaAuthorizeRequestWithBody(\"test\") -\u003e upstream`:\n- `{\"action\":\"delete\"}` (19B ≤ 32) → **403** (denied).\n- `{\"action\":\"delete\",\"pad\":\"X..64\"}` (\u003e 32) → **200**, upstream received the full body (BYPASS).\n- small chunked `{\"action\":\"delete\"}` → **403** (positive control: the original CVE is fixed).\n\n(Library-tier: validated via Skipper's real proxy test harness, not a deploy of the official image; benign\noracle = status diff + upstream-received body; no RCE.)\n\n### Impact\n\nDeployments authorizing on request-body content via `opaAuthorizeRequestWithBody` + deny-on-presence Rego\ncan be bypassed by inflating the request body past `-open-policy-agent-max-request-body-size` (default\n1 MB); the full payload still reaches the upstream.\n\n### Mitigation\n\nDocument how policy owners should block requests with oversized body.\n\nExample deny by default and use \"allow if\" no oversized body:\n```rego\ndefault allow := false\n\nallow if {\n    input.attributes.request.http.truncated_body == false\n    # ... body-based conditions\n}\n```\n\nExample allow by default and use \"deny if\" an oversized body:\n```rego\ndefault deny := false\n\ndeny if {\n    input.attributes.request.http.truncated_body == true\n    # ... body-based conditions\n}\n```\n\nDocumentation is published by https://github.com/zalando/skipper/releases/tag/v0.27.26\n\n### Credit\n\nReported as part of an incomplete-patch measurement study (responsible disclosure).","status":"published","published":"2026-07-17T21:49:48Z","modified":"2026-09-25T17:15:05.948244239Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high"}],"cwes":["CWE-444"],"updated_at":"2026-11-02T15:46:42.78452Z"},{"id":"GO-2026-6019","title":"Skipper: Incomplete fix for CVE-2026-50197: an oversized body can bypass OPA deny-on-presence Rego policies in github.com/zalando/skipper","description":"Skipper: Incomplete fix for CVE-2026-50197: an oversized body can bypass OPA deny-on-presence Rego policies in github.com/zalando/skipper","status":"published","published":"2026-07-22T20:36:35Z","modified":"2026-09-15T11:55:56.999383354Z","updated_at":"2026-11-02T15:47:02.838915Z"}]}}