Vulnerability · Published Oct 22, 2026 · Assigned by GitHub_M
CVE-2026-114620Authlib: Unvalidated request_uri fetch in JWT-secured authorization request (JAR) leading to SSRF
Medium 5.4
In plain English
A medium-severity server-side request forgery in authlib from authlib. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | python-authlib | no fix listed | DEBIAN-CVE-2026-114620 |
| Debian:13 | python-authlib | no fix listed | DEBIAN-CVE-2026-114620 |
| Debian:14 | python-authlib | 1.9.1-1 | DEBIAN-CVE-2026-114620 |
| PyPI | authlib | 1.9.0 | GHSA-x4rv-c3wx-4cr8 |
| PyPI | authlib | 1.9.0 | PYSEC-2026-4360 |
| Ubuntu:26.10 | python-authlib | no fix listed | UBUNTU-CVE-2026-114620 |
Affected products (as reported)
Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
References
- https://github.com/authlib/authlib/security/advisories/GHSA-x4rv-c3wx-4cr8 x_refsource_CONFIRM
- https://github.com/authlib/authlib/pull/949 x_refsource_MISC
- https://github.com/authlib/authlib/commit/6563f6f7a8c2f71d2f85ee7511d72a4fbae3acc0 x_refsource_MISC
- https://github.com/authlib/authlib/commit/891e3f10ae5989176211f8be35dcc7cd40aa92c6 x_refsource_MISC
- https://github.com/authlib/authlib/releases/tag/v1.9.0 x_refsource_MISC