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Vulnerability · Published Sep 7, 2026 · Assigned by EEF

CVE-2026-81638Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry

Low 2.1

In plain English

A low-severity security flaw in ash_double_entry from ash-project. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities).

Severity (CVSS 4.0)2.1Low
Exploit odds (30 days)0.2%top 91.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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. 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. This issue affects ash_double_entry: from 0.1.0 before 1.0.19.

Affected products (as reported)

VendorProductVersions
ash-project ash_double_entry 0.1.0 – before 1.0.19
ash-project ash_double_entry 1e5f7ce8ff25f519c904731a29eb1258324e561a – before d3e688d300a581ae214b3ca7d95ef4de63fbb050

Weakness: CWE-173 · 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

References