CVE-2026-82753 Denial of service in ash authentication oauth2 server
Unauthenticated attackers can exhaust database and memory resources by creating unlimited client rows via the authorize endpoint when CIMD is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-82753?
CVE-2026-82753 is a high-severity denial of service vulnerability in ash-project ash_authentication_oauth2_server, published on 7 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-770
Which versions are affected by CVE-2026-82753?
1 open source package ship an affected version, including ash_authentication_oauth2_server.
| Package | Affected | Fixed in |
|---|---|---|
ash_authentication_oauth2_server Hex | From 0.3.0 | 0.3.1 |
How do I fix CVE-2026-82753?
Upgrade ash_authentication_oauth2_server to 0.3.1 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-82753 being exploited?
There is no known exploitation of CVE-2026-82753 in the wild and no public exploit code.
Sources
Also known as EEF-CVE-2026-82753, GHSA-9pv3-wxjm-f846.