Signal is active with 1 mentions in latest observed window
Recommended action window: Monitor and triage in normal cycle
NVD description
Authlib is a Python library which builds OAuth and OpenID Connect servers. From 0.15 until 1.9.1, the documented ClientConfigurationEndpoint.authenticate_client and ClientConfigurationEndpoint.check_permission reference implementations look up a target client from request-controlled client_id data and check only whether that target is editable, without verifying that request.credential belongs to the target client. Deployments following both examples can allow a client holding any valid registration access token to read, modify, or delete another client's registration. Changing redirect_uris can enable authorization code or token interception, while deleting registrations can deny service to affected clients. This issue is fixed in version 1.9.1.
Priority
LOW
Exploitation
NONE
PoC
NONE
Patch
NONE
Momentum
STABLE
CVE-2026-116672 affects Authlib OAuth/OIDC servers. An authorisation bypass can let attackers modify other clients’ registrations, hijack redirect URIs and intercept authentication tokens. Analysis: https://github.com/alan-turing-institute/cyber-threat-observatory/blob/main/reports/2026-10-27/TIER_2_CVE-2026-116672.md #CyberSecurity #DigitalIdentity #OAuth
🚨HIGH - Authlib OAuth/OIDC Dynamic Client Registration Takeover (CVE-2026-116672) Authlib’s documented reference impls for OAuth/OIDC client config endpoints use request-controlled client_id to select the target client and only check “editable” without verifying the registration_access_token belongs to that client. Any client with a valid registration access token can read/modify/delete other clients’ registrations, enabling redirect_uri swaps to steal codes/tokens or DoS via deletion. 👉Affected: Authlib/authlib < 1.9.1 | Upgrade to 1.9.1