Is CVE-2026-81638 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-81638 being exploited in the wild.

How severe is CVE-2026-81638?

Informational severity, published 7 September 2026.

Which products and versions are affected?

Ash-Project Ash Double Entry 0.1.0 to 1.0.18 (fixed in 1.0.19).

Is there a fix for CVE-2026-81638?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-81638 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-81638?

Check whether you run Ash-Project Ash Double Entry at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-81638: ash-project ash_double_entry ULID encoding bypass

CVE-2026-81638 · Severity: info · Published 2026-09-07

AshDoubleEntry is a library used to implement double-entry bookkeeping in Elixir applications. A flaw in ULID encoding allows attackers to submit multiple distinct spellings of the same identifier, bypassing string-level security controls like deduplication checks, idempotency keys, and audit logs. This could allow attackers to manipulate transaction records or evade security controls in financial applications.

Vendors: Ash-Project.

Quick answers

Is CVE-2026-81638 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-81638 being exploited in the wild.
How severe is CVE-2026-81638?: Informational severity, published 7 September 2026.
Which products and versions are affected?: Ash-Project Ash Double Entry 0.1.0 to 1.0.18 (fixed in 1.0.19).
Is there a fix for CVE-2026-81638?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-81638 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-81638?: Check whether you run Ash-Project Ash Double Entry at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is an improper handling of alternate encoding in the ULID (Universally Unique Lexicographically Sortable Identifier) implementation. The decode/1 function in lib/ulid.ex masks the first character to its low 3 bits, but valid?/1 accepts all 32 Crockford base-32 characters in that position, allowing characters 0–7, 8–F, G–O, and R–Z to encode to the same 128-bit value. This allows multiple string representations (e.g., "0...", "8...", "G...", "R...") to resolve to identical database rows. When ULIDs are used as public identifiers over HTTP/API boundaries, an attacker can submit an alternate encoding to desynchronize checks keyed on the canonical form.

Affected products

ash-project ash_double_entry 0.1.0 to 1.0.18 (fixed in 1.0.19)

Timeline

2026-09-07: disclosed

References

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