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.
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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| ash-project | ash_double_entry | unaffected |
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| ash-project | ash_double_entry | unaffected |
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Advisories
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Fixes
Solution
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Workaround
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References
History
Mon, 07 Sep 2026 22:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry | |
| First Time appeared |
Ash-project
Ash-project ash Double Entry |
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| Weaknesses | CWE-173 | |
| CPEs | cpe:2.3:a:ash-project:ash_double_entry:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Ash-project
Ash-project ash Double Entry |
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| References |
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| Metrics |
cvssV4_0
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Projects
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MITRE
Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-09-07T22:33:29.297Z
Reserved: 2026-09-07T19:30:01.624Z
Link: CVE-2026-81638
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
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Weaknesses