VulnerabilityDeferred

CVE-2026-81638

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.

LOW 2.1EPSS 0.13%

Does this matter?

Lower severity and a low EPSS score (0.13%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 4.0: 2.1 LOWCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.13% probability · 3th percentile
CISA KEV: Not listed
Weakness: CWE-173
Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.