{"id":"CVE-2026-81638","aliases":["EEF-CVE-2026-81638","EUVD-2026-72541","GHSA-qxp2-vgp9-268q"],"status":"published","title":"Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry","description":"Improper Handling of Alternate Encoding vulnerability in ash-project ash_double_entry allows an attacker to submit several distinct string spellings of the same identifier.\n\nAshDoubleEntry.ULID renders a 128-bit ULID as 26 Crockford base-32 characters, but the first character encodes only 3 bits, so canonical values are 0 to 7. decode/1 in lib/ulid.ex masks the first character to its low 3 bits and valid?/1 accepts all 32 characters in that position, so 0..., 8..., G... and R... decode to the identical 16-byte value and resolve to the same row. When the type is exposed as a public ID over an HTTP or API boundary, an attacker-supplied ID can be spelled differently from the record it actually reads or writes, desynchronizing or bypassing string-level checks such as idempotency and deduplication keys, deny-lists, audit correlation, or signatures computed over the submitted ID.\n\nThis issue affects ash_double_entry: from 0.1.0 before 1.0.19.","severity":{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","level":"low","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00189,"percentile":0.08604,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-173"],"published":"2026-09-07T22:33:29Z","modified":"2026-10-28T02:30:33Z","fixes":[{"ecosystem":"Hex","package":"ash_double_entry","fixed_in":["1.0.19"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Hex","package":"ash_double_entry","ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.0"},{"fixed":"1.0.19"}]}],"versions":["0.1.0","0.1.1","0.1.2","0.2.0","0.2.1","0.2.2","0.2.3","0.2.4","1.0.0","1.0.0-rc.0","1.0.1","1.0.10","1.0.11","1.0.12","1.0.13","1.0.14","1.0.15","1.0.16","1.0.17","1.0.18","1.0.2","1.0.3","1.0.4","1.0.5","1.0.6","1.0.7","1.0.8","1.0.9"]}],"products":[{"vendor":"ash-project","product":"ash_double_entry"}],"references":[{"url":"https://github.com/ash-project/ash_double_entry/security/advisories/GHSA-qxp2-vgp9-268q","tags":["vendor-advisory","related","advisory"]},{"url":"https://cna.erlef.org/cves/CVE-2026-81638.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-81638","tags":["related","web"]},{"url":"https://github.com/ash-project/ash_double_entry/commit/d3e688d300a581ae214b3ca7d95ef4de63fbb050","tags":["patch","fix"]},{"url":"https://github.com","tags":["web"]},{"url":"https://repo.hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81638.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-81638","tags":["advisory"]},{"url":"https://github.com/ash-project/ash_double_entry","tags":["package"]},{"url":"https://hex.pm/packages/ash_double_entry","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-81638","title":"Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry","description":"Improper Handling of Alternate Encoding vulnerability in ash-project ash_double_entry allows an attacker to submit several distinct string spellings of the same identifier.\n\nAshDoubleEntry.ULID renders a 128-bit ULID as 26 Crockford base-32 characters, but the first character encodes only 3 bits, so canonical values are 0 to 7. decode/1 in lib/ulid.ex masks the first character to its low 3 bits and valid?/1 accepts all 32 characters in that position, so 0..., 8..., G... and R... decode to the identical 16-byte value and resolve to the same row. When the type is exposed as a public ID over an HTTP or API boundary, an attacker-supplied ID can be spelled differently from the record it actually reads or writes, desynchronizing or bypassing string-level checks such as idempotency and deduplication keys, deny-lists, audit correlation, or signatures computed over the submitted ID.\n\nThis issue affects ash_double_entry: from 0.1.0 before 1.0.19.","status":"published","published":"2026-09-07T22:33:29.297Z","modified":"2026-09-08T14:44:19.138Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","level":"low","assessor":"cna"}],"cwes":["CWE-173"],"updated_at":"2026-11-02T13:36:18.075535Z"}],"euvd":[{"id":"EUVD-2026-72541","description":"Improper Handling of Alternate Encoding vulnerability in ash-project ash_double_entry allows an attacker to submit several distinct string spellings of the same identifier.\n\nAshDoubleEntry.ULID renders a 128-bit ULID as 26 Crockford base-32 characters, but the first character encodes only 3 bits, so canonical values are 0 to 7. decode/1 in lib/ulid.ex masks the first character to its low 3 bits and valid?/1 accepts all 32 characters in that position, so 0..., 8..., G... and R... decode to the identical 16-byte value and resolve to the same row. When the type is exposed as a public ID over an HTTP or API boundary, an attacker-supplied ID can be spelled differently from the record it actually reads or writes, desynchronizing or bypassing string-level checks such as idempotency and deduplication keys, deny-lists, audit correlation, or signatures computed over the submitted ID.\n\nThis issue affects ash_double_entry: from 0.1.0 before 1.0.19.","status":"published","published":"2026-09-07T22:33:29Z","modified":"2026-09-08T14:44:19Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","level":"low"}],"updated_at":"2026-11-02T17:28:29.426Z"}],"nvd":[{"id":"CVE-2026-81638","description":"Improper Handling of Alternate Encoding vulnerability in ash-project ash_double_entry allows an attacker to submit several distinct string spellings of the same identifier.\n\nAshDoubleEntry.ULID renders a 128-bit ULID as 26 Crockford base-32 characters, but the first character encodes only 3 bits, so canonical values are 0 to 7. decode/1 in lib/ulid.ex masks the first character to its low 3 bits and valid?/1 accepts all 32 characters in that position, so 0..., 8..., G... and R... decode to the identical 16-byte value and resolve to the same row. When the type is exposed as a public ID over an HTTP or API boundary, an attacker-supplied ID can be spelled differently from the record it actually reads or writes, desynchronizing or bypassing string-level checks such as idempotency and deduplication keys, deny-lists, audit correlation, or signatures computed over the submitted ID.\n\nThis issue affects ash_double_entry: from 0.1.0 before 1.0.19.","status":"published","published":"2026-09-07T23:16:51.757Z","modified":"2026-09-08T15:18:49.077Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"low","assessor":"secondary"}],"cwes":["CWE-173"],"updated_at":"2026-11-02T14:12:44.436435Z"}],"osv":[{"id":"CVE-2026-81638","title":"Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry","description":"Improper Handling of Alternate Encoding vulnerability in ash-project ash_double_entry allows an attacker to submit several distinct string spellings of the same identifier.\n\nAshDoubleEntry.ULID renders a 128-bit ULID as 26 Crockford base-32 characters, but the first character encodes only 3 bits, so canonical values are 0 to 7. decode/1 in lib/ulid.ex masks the first character to its low 3 bits and valid?/1 accepts all 32 characters in that position, so 0..., 8..., G... and R... decode to the identical 16-byte value and resolve to the same row. When the type is exposed as a public ID over an HTTP or API boundary, an attacker-supplied ID can be spelled differently from the record it actually reads or writes, desynchronizing or bypassing string-level checks such as idempotency and deduplication keys, deny-lists, audit correlation, or signatures computed over the submitted ID.\n\nThis issue affects ash_double_entry: from 0.1.0 before 1.0.19.","status":"published","published":"2026-09-07T22:33:29.297Z","modified":"2026-10-28T02:30:33.184077502Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","level":"low"}],"cwes":["CWE-173"],"updated_at":"2026-11-02T15:45:18.131258Z"},{"id":"EEF-CVE-2026-81638","title":"Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry","description":"## Summary\n\nImproper Handling of Alternate Encoding vulnerability in ash-project ash_double_entry allows an attacker to submit several distinct string spellings of the same identifier.\n\n`AshDoubleEntry.ULID` renders a 128-bit ULID as 26 Crockford base-32 characters, but the first character encodes only 3 bits, so canonical values are `0` to `7`. `decode/1` in `lib/ulid.ex` masks the first character to its low 3 bits and `valid?/1` accepts all 32 characters in that position, so `0...`, `8...`, `G...` and `R...` decode to the identical 16-byte value and resolve to the same row. When the type is exposed as a public ID over an HTTP or API boundary, an attacker-supplied ID can be spelled differently from the record it actually reads or writes, desynchronizing or bypassing string-level checks such as idempotency and deduplication keys, deny-lists, audit correlation, or signatures computed over the submitted ID.\n\nThis issue affects ash_double_entry: from 0.1.0 before 1.0.19.\n\n## Configurations\n\nReachable only when an application exposes `AshDoubleEntry.ULID` as a public identifier over an HTTP or API boundary and performs string-level checks on the submitted ID (idempotency or deduplication keys, deny-lists, audit correlation, or signatures) rather than treating the value as opaque.","status":"published","published":"2026-09-07T22:33:29.297Z","modified":"2026-09-08T22:45:03.325254394Z","cvss":[{"version":"4.0","score":2.1,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N","level":"low"}],"cwes":["CWE-173"],"updated_at":"2026-11-02T15:46:33.520522Z"}]}}