{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-81638", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-09-07T19:30:01.624Z", "datePublished": "2026-09-07T22:33:29.297Z", "dateUpdated": "2026-09-07T22:33:29.297Z"}, "containers": {"cna": {"affected": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:ash-project:ash_double_entry:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.AshDoubleEntry.ULID'"], "packageName": "ash_double_entry", "packageURL": "pkg:hex/ash_double_entry", "product": "ash_double_entry", "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", "versions": [{"lessThan": "1.0.19", "status": "affected", "version": "0.1.0", "versionType": "semver"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:ash-project:ash_double_entry:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.AshDoubleEntry.ULID'"], "packageName": "ash-project/ash_double_entry", "packageURL": "pkg:github/ash-project/ash_double_entry", "product": "ash_double_entry", "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", "versions": [{"lessThan": "d3e688d300a581ae214b3ca7d95ef4de63fbb050", "status": "affected", "version": "1e5f7ce8ff25f519c904731a29eb1258324e561a", "versionType": "git"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Reachable only when an application exposes <code>AshDoubleEntry.ULID</code> 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.</p>"}, {"base64": false, "type": "text/markdown", "value": "Reachable 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."}], "value": "Reachable 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."}], "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 M\u00e4nnchen / EEF"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>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.</p>\n<p><code>AshDoubleEntry.ULID</code> renders a 128-bit ULID as 26 Crockford base-32 characters, but the first character encodes only 3 bits, so canonical values are <code>0</code> to <code>7</code>. <code>decode/1</code> in <code>lib/ulid.ex</code> masks the first character to its low 3 bits and <code>valid?/1</code> accepts all 32 characters in that position, so <code>0...</code>, <code>8...</code>, <code>G...</code> and <code>R...</code> 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.</p>\n<p>This issue affects ash_double_entry: from 0.1.0 before 1.0.19.</p>"}, {"base64": false, "type": "text/markdown", "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\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."}], "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."}], "impacts": [{"capecId": "CAPEC-267", "descriptions": [{"lang": "en", "value": "CAPEC-267 Leverage Alternate Encoding"}]}], "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 Improper Handling of Alternate Encoding", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-09-07T22:33:29.297Z"}, "references": [{"tags": ["vendor-advisory", "related"], "url": "https://github.com/ash-project/ash_double_entry/security/advisories/GHSA-qxp2-vgp9-268q"}, {"tags": ["related"], "url": "https://cna.erlef.org/cves/CVE-2026-81638.html"}, {"tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-81638"}, {"tags": ["patch"], "url": "https://github.com/ash-project/ash_double_entry/commit/d3e688d300a581ae214b3ca7d95ef4de63fbb050"}], "source": {"discovery": "EXTERNAL"}, "title": "Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry"}}}

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