{"id":"CVE-2026-81638","state":"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.","publishedAt":"2026-09-07T22:33:29.297Z","updatedAt":"2026-09-08T14:44:19.138Z","severity":{"score":2.1,"label":"Low","version":"4.0","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","source":"EEF"},"assigner":"EEF","products":["ash-project ash_double_entry"],"affected":[{"vendor":"ash-project","product":"ash_double_entry","packageName":"ash_double_entry","packageURL":"pkg:hex/ash_double_entry","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"1.0.19","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ash-project:ash_double_entry:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshDoubleEntry.ULID'"],"programFiles":["lib/ulid.ex"],"programRoutines":[{"name":"'Elixir.AshDoubleEntry.ULID':cast_input/2"},{"name":"'Elixir.AshDoubleEntry.ULID':dump_to_native/2"}],"repo":"https://github.com/ash-project/ash_double_entry"},{"vendor":"ash-project","product":"ash_double_entry","packageName":"ash-project/ash_double_entry","packageURL":"pkg:github/ash-project/ash_double_entry","defaultStatus":"unaffected","versions":[{"version":"1e5f7ce8ff25f519c904731a29eb1258324e561a","status":"affected","lessThan":"d3e688d300a581ae214b3ca7d95ef4de63fbb050","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ash-project:ash_double_entry:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshDoubleEntry.ULID'"],"programFiles":["lib/ulid.ex"],"programRoutines":[{"name":"'Elixir.AshDoubleEntry.ULID':cast_input/2"},{"name":"'Elixir.AshDoubleEntry.ULID':dump_to_native/2"}],"repo":"https://github.com/ash-project/ash_double_entry"}],"references":["https://github.com/ash-project/ash_double_entry/security/advisories/GHSA-qxp2-vgp9-268q","https://cna.erlef.org/cves/CVE-2026-81638.html","https://osv.dev/vulnerability/EEF-CVE-2026-81638","https://github.com/ash-project/ash_double_entry/commit/d3e688d300a581ae214b3ca7d95ef4de63fbb050"],"weaknesses":["CWE-173"],"ingestedAt":"2026-10-29T20:13:15.269Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/81xxx/CVE-2026-81638.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-81638","state":"PUBLISHED","datePublished":"2026-09-07T22:33:29.297Z","dateUpdated":"2026-09-08T14:44:19.138Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-09-07T19:30:01.624Z"},"containers":{"cna":{"title":"Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"ash-project","product":"ash_double_entry","packageName":"ash_double_entry","packageURL":"pkg:hex/ash_double_entry","defaultStatus":"unaffected","versions":[{"version":"0.1.0","status":"affected","lessThan":"1.0.19","versionType":"semver"}],"collectionURL":"https://repo.hex.pm","cpes":["cpe:2.3:a:ash-project:ash_double_entry:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshDoubleEntry.ULID'"],"programFiles":["lib/ulid.ex"],"programRoutines":[{"name":"'Elixir.AshDoubleEntry.ULID':cast_input/2"},{"name":"'Elixir.AshDoubleEntry.ULID':dump_to_native/2"}],"repo":"https://github.com/ash-project/ash_double_entry"},{"vendor":"ash-project","product":"ash_double_entry","packageName":"ash-project/ash_double_entry","packageURL":"pkg:github/ash-project/ash_double_entry","defaultStatus":"unaffected","versions":[{"version":"1e5f7ce8ff25f519c904731a29eb1258324e561a","status":"affected","lessThan":"d3e688d300a581ae214b3ca7d95ef4de63fbb050","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:ash-project:ash_double_entry:*:*:*:*:*:*:*:*"],"modules":["'Elixir.AshDoubleEntry.ULID'"],"programFiles":["lib/ulid.ex"],"programRoutines":[{"name":"'Elixir.AshDoubleEntry.ULID':cast_input/2"},{"name":"'Elixir.AshDoubleEntry.ULID':dump_to_native/2"}],"repo":"https://github.com/ash-project/ash_double_entry"}],"references":[{"url":"https://github.com/ash-project/ash_double_entry/security/advisories/GHSA-qxp2-vgp9-268q","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-81638.html","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-81638","tags":["related"]},{"url":"https://github.com/ash-project/ash_double_entry/commit/d3e688d300a581ae214b3ca7d95ef4de63fbb050","tags":["patch"]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"PRESENT","attackVector":"LOCAL","baseScore":2.1,"baseSeverity":"LOW","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"LOW","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"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","version":"4.0","vulnAvailabilityImpact":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"LOW","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-173","description":"CWE-173 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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."}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:ash-project:ash_double_entry:*:*:*:*:*:*:*:*","versionEndExcluding":"1.0.19","versionStartIncluding":"0.1.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"Peter Ullrich"},{"lang":"en","type":"reporter","value":"Peter Ullrich"},{"lang":"en","type":"remediation developer","value":"Zach Daniel / Ash Project"},{"lang":"en","type":"coordinator","value":"Jonatan Männchen / EEF"}],"impacts":[{"capecId":"CAPEC-267","descriptions":[{"lang":"en","value":"CAPEC-267 Leverage Alternate Encoding"}]}],"source":{"discovery":"EXTERNAL"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-08T14:44:11.859893Z","id":"CVE-2026-81638","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-08T14:44:19.138Z"}}]}}}