Description (CNA)
Improper Encoding or Escaping of Output vulnerability in ash-project ash_authentication_oauth2_server allows an unauthenticated attacker to inject arbitrary authentication parameters into the WWW-Authenticate challenge header. BearerPlug and RequireScopePlug built the Bearer resource_metadata="..." challenge by interpolating a resource_metadata URL derived from the request tenant directly into the quoted value. In a multi-tenant application that sets the Ash tenant from request-controlled data (a subdomain, the Host, a path segment, or a header), a tenant containing a " closes the quoted value and appends attacker-chosen auth-params, including a second resource_metadata URL pointing at an attacker-controlled authorization server that spec-following clients follow. Carriage returns and line feeds are rejected by Plug, so this is parameter injection within one header, not response splitting. This issue affects ash_authentication_oauth2_server: from 0.1.3 before 0.3.1.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| ash-project / ash_authentication_oauth2_server | affected 0.1.3 before 0.3.1 |
| ash-project / ash_authentication_oauth2_server | affected 99de0a1cacb5ef667c4533278b7c81ca98c00231 before 09f97476715da031b136eaec7b2cda2363ad8149 |
CWE
CWE-116
References
- https://github.com/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-2h3v-83jg-2qmm
- https://cna.erlef.org/cves/CVE-2026-82756.html
- https://osv.dev/vulnerability/EEF-CVE-2026-82756
- https://github.com/ash-project/ash_authentication_oauth2_server/commit/09f97476715da031b136eaec7b2cda2363ad8149
ADP enrichment
No English description supplied.
No references supplied.