Authlib: is_secure_transport() loopback exemption can be bypassed with a userinfo component, allowing cleartext-HTTP URLs to non-loopback hosts

影響: pip:authlib <= 1.7.2 → 1.8.0

authlib.common.security.is_secure_transport() is used throughout Authlib to enforce the OAuth 2.0 / OIDC requirement that endpoint and redirect URIs use TLS, with an RFC 8252 §7.3 exemption for loopback http:// URIs. The check is implemented as a textual str.startswith prefix match, so a URL such as http://localhost:80@evil.example/cb — whose actual host is evil.example and whose scheme is plain http — is accepted as "secure". An attacker who can supply a URL to any of the sinks that rely on th…

Read on GitHub Advisory Database

On 10/28/2026, 12:37 AM, GitHub Advisory Database published "Authlib: is_secure_transport() loopback exemption can be bypassed with a userinfo component, allowing cleartext-HTTP URLs to non-loopback hosts" (type: Advisory). Severity is "Low" (low). Related technologies: Python. CVE: CVE-2026-114614.