CVE-2026-82755
Description
Use of Cache Containing Sensitive Information vulnerability in ash-project ash_authentication_oauth2_server allows a shared HTTP cache to serve one tenant's OAuth discovery metadata to another tenant's clients. The RFC 8414 and RFC 9728 metadata endpoints in AshAuthentication.Phoenix.Oauth2Server.ProtocolRouter return tenant-specific values (issuer, authorization_endpoint, token_endpoint, jwks_uri) when a tenant is set, but sent them with Cache-Control: public, max-age=3600 and no Vary. When the tenant is derived from something other than the URL (a header or the Host) and a shared cache sits in front, the cache key is the URL alone, so a stored response for one tenant is served to another for up to an hour. Affected clients may then send authorization codes and secrets to the wrong tenant's token endpoint and validate tokens against the wrong keys. This issue affects ash_authentication_oauth2_server: from 0.1.3 before 0.3.1.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
Propose a mitigation on Community Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
Package impact
| Ecosystem | Package | Vulnerable | Fixed |
|---|---|---|---|
| Hex | ash_authentication_oauth2_server | >=0.1.3,<0.3.1 | 0.3.1 |
References
- https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-crqf-7m54-4hgc
- https://cna.erlef.org/cves/CVE-2026-82755.html
- https://github.com/ash-project/ash_authentication_oauth2_server/commit/768d87f70e4e97ae1d2bf1606b5bf3f4d03f24a1
- https://hex.pm/packages/ash_authentication_oauth2_server
- https://osv.dev/vulnerability/EEF-CVE-2026-82755
CWEs
CWE-524
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.