{"id":"PYSEC-2026-4360","details":"Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.0, Authlib's RFC 9101 JWTAuthenticationRequest passes the unauthenticated, client-controlled request_uri parameter to the abstract get_request_object() hook before applying a destination or registration policy; the hook itself performs no network request, while the documentation demonstrates an unrestricted HTTP fetch. In deployments whose integrator implements that hook as an unrestricted outbound fetch, a remote attacker who knows a valid public client identifier can make the authorization server request internal, link-local, or otherwise unintended URLs and can distinguish fetch outcomes through different error responses and timing. Deployments whose custom hook already applies a secure allowlist, destination controls, and retrieval limits are not affected. The JWTAuthenticationRequest implementation in authlib/oauth2/rfc9101/authorization_server.py forwards request_uri to get_request_object() before an application-approved retrieval policy accepts the destination. This issue is fixed in version 1.9.0.","aliases":["CVE-2026-114620","GHSA-x4rv-c3wx-4cr8"],"modified":"2026-10-30T10:00:02.215927425Z","published":"2026-10-22T22:18:05.090Z","references":[{"type":"ADVISORY","url":"https://github.com/authlib/authlib/releases/tag/v1.9.0"},{"type":"FIX","url":"https://github.com/authlib/authlib/commit/6563f6f7a8c2f71d2f85ee7511d72a4fbae3acc0"},{"type":"FIX","url":"https://github.com/authlib/authlib/commit/891e3f10ae5989176211f8be35dcc7cd40aa92c6"},{"type":"FIX","url":"https://github.com/authlib/authlib/pull/949"},{"type":"EVIDENCE","url":"https://github.com/authlib/authlib/security/advisories/GHSA-x4rv-c3wx-4cr8"}],"affected":[{"package":{"name":"authlib","ecosystem":"PyPI","purl":"pkg:pypi/authlib"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.6.0"},{"fixed":"1.9.0"}]}],"versions":["1.6.0","1.6.1","1.6.10","1.6.11","1.6.12","1.6.2","1.6.3","1.6.4","1.6.5","1.6.6","1.6.7","1.6.8","1.6.9","1.7.0","1.7.1","1.7.2","1.8.0"],"ecosystem_specific":{},"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/authlib/PYSEC-2026-4360.yaml"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N"}]}