| Name | CVE-2025-59420 |
| Description | Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.4, Authlib’s JWS verification accepts tokens that declare unknown critical header parameters (crit), violating RFC 7515 “must‑understand” semantics. An attacker can craft a signed token with a critical header (for example, bork or cnf) that strict verifiers reject but Authlib accepts. In mixed‑language fleets, this enables split‑brain verification and can lead to policy bypass, replay, or privilege escalation. This issue has been patched in version 1.6.4. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| python-authlib (PTS) | bullseye | 0.15.4-1 | vulnerable |
| bookworm | 1.2.0-1 | vulnerable | |
| trixie | 1.6.0-1 | vulnerable | |
| forky, sid | 1.6.4-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| python-authlib | source | (unstable) | 1.6.4-1 |
https://github.com/authlib/authlib/security/advisories/GHSA-9ggr-2464-2j32
https://github.com/authlib/authlib/commit/6b1813e4392eb7c168c276099ff7783b176479df (v1.6.4)