{"id":"CVE-2026-81638","title":"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…","summary":"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…","severity":"low","cvss":2.1,"cvssVector":"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","cwe":["CWE-173"],"vendor":"ash-project","product":"ash_double_entry","affected":["ash_double_entry >= 0.1.0 < 1.0.19","ash-project/ash_double_entry >= 1e5f7ce8ff25f519c904731a29eb1258324e561a < d3e688d300a581ae214b3ca7d95ef4de63fbb050"],"published":"2026-09-07","updated":"2026-09-08","sourceUpdated":"2026-09-08T15:18:49.077","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-81638","references":[{"url":"https://cna.erlef.org/cves/CVE-2026-81638.html","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/ash-project/ash_double_entry/commit/d3e688d300a581ae214b3ca7d95ef4de63fbb050","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/ash-project/ash_double_entry/security/advisories/GHSA-qxp2-vgp9-268q","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-81638","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-09-08T14:44:11.859893Z"},"cvssSource":"cna","epss":0.00133,"epssPercentile":0.03183,"ingestedAt":"2026-09-08T15:33:26.980Z","slug":"CVE-2026-81638","body":"## Overview\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\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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":12,"depthScoreParts":{"impact":11.6,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}