CVE-2026-81638

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Source
https://cve.org/CVERecord?id=CVE-2026-81638
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-81638.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-81638
Aliases
Published
2026-09-07T22:33:29Z
Modified
2026-09-10T03:30:44Z
Severity
  • 2.1 (Low) CVSS_V4 - 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 CVSS Calculator
Summary
Non-canonical ULID spellings are accepted and alias to the same record in ash_double_entry
Details

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.

Database specific 
{
    "cna_assigner": "EEF",
    "cwe_ids": [
        "CWE-173"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81638.json",
    "unresolved_ranges": [
        {
            "extracted_events": [
                {
                    "introduced": "1e5f7ce8ff25f519c904731a29eb1258324e561a"
                },
                {
                    "fixed": "d3e688d300a581ae214b3ca7d95ef4de63fbb050"
                }
            ],
            "source": "AFFECTED_FIELD"
        }
    ]
}
References

Affected packages

Git / github.com/ash-project/ash_double_entry

Affected ranges

Type
GIT
Repo
https://github.com/ash-project/ash_double_entry
Events
Introduced
617f6c2cd7eb1ffd5b71701e76f9c3700e0ae415
Fixed
038e2fa8b1b61c94f39a8d6e494912eb6c0073b8
Fixed
d3e688d300a581ae214b3ca7d95ef4de63fbb050
Database specific
Show details 
{
    "extracted_events": [
        {
            "introduced": "0.1.0"
        },
        {
            "fixed": "1.0.19"
        }
    ],
    "source": [
        "DESCRIPTION",
        "REFERENCES"
    ]
}

Affected versions

v0.*
v0.1.0
v0.1.1
v0.1.2
v0.2.0
v0.2.1
v0.2.2
v0.2.3
v0.2.4
v1.*
v1.0.0
v1.0.0-rc.0
v1.0.0-rc.1
v1.0.1
v1.0.10
v1.0.11
v1.0.12
v1.0.13
v1.0.14
v1.0.15
v1.0.16
v1.0.17
v1.0.18
v1.0.2
v1.0.3
v1.0.4
v1.0.5
v1.0.6
v1.0.7
v1.0.8
v1.0.9

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-81638.json"