{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.1.0"
              },
              {
                "fixed": "1.0.19"
              }
            ],
            "source": [
              "DESCRIPTION",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "617f6c2cd7eb1ffd5b71701e76f9c3700e0ae415"
            },
            {
              "fixed": "038e2fa8b1b61c94f39a8d6e494912eb6c0073b8"
            },
            {
              "fixed": "d3e688d300a581ae214b3ca7d95ef4de63fbb050"
            }
          ],
          "repo": "https://github.com/ash-project/ash_double_entry",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-qxp2-vgp9-268q"
  ],
  "database_specific": {
    "cna_assigner": "EEF",
    "cwe_ids": [
      "CWE-173"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81638.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "1e5f7ce8ff25f519c904731a29eb1258324e561a"
          },
          {
            "fixed": "d3e688d300a581ae214b3ca7d95ef4de63fbb050"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "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.",
  "id": "CVE-2026-81638",
  "modified": "2026-09-10T03:30:44.236271399Z",
  "published": "2026-09-07T22:33:29.297Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-81638.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-81638"
    },
    {
      "type": "WEB",
      "url": "https://repo.hex.pm"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81638.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/ash-project/ash_double_entry/security/advisories/GHSA-qxp2-vgp9-268q"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-81638"
    },
    {
      "type": "FIX",
      "url": "https://github.com/ash-project/ash_double_entry/commit/d3e688d300a581ae214b3ca7d95ef4de63fbb050"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ash-project/ash_double_entry"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry"
}