Integrity-check bypass via non-canonical ULID aliases
Published Sep 7, 2026 · Updated Sep 8, 2026
Improper alternate-encoding handling in Ash Framework AshDoubleEntry before 1.0.19 allows remote attackers to bypass ID-based checks. The decode/1 routine masks the first Crockford character to three bits while valid?/1 accepts all 32 values, letting distinct strings resolve to the same 16-byte ULID and database row. Exposure requires an application to publish the ULID as an HTTP or API identifier and rely on its submitted spelling for deduplication, deny-lists, audit correlation, or signatures.
Summary
What happened
Improper alternate-encoding handling in Ash Framework AshDoubleEntry before 1.0.19 allows remote attackers to bypass ID-based checks. The decode/1 routine masks the first Crockford character to three bits while valid?/1 accepts all 32 values, letting distinct strings resolve to the same 16-byte ULID and database row. Exposure requires an application to publish the ULID as an HTTP or API identifier and rely on its submitted spelling for deduplication, deny-lists, audit correlation, or signatures.
The record
- CVE
- CVE-2026-81638
- Published
- Sep 7, 2026
- Updated
- Sep 8, 2026
- Vendor
- Ash Framework
- Product
- AshDoubleEntry
- Classifications
- CWE-173, CAPEC-267
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 7, 2026CVE publishedPublication date reported by the CVE source.
- Sep 8, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.1.0 <1.0.19
- Affected versionversion=1e5f7ce8ff25f519c904731a29eb1258324e561a <d3e688d300a581ae214b3ca7d95ef4de63fbb050
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Technologies
Your stack
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Your stack
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