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Debian LTS Advisory DLA-4708-1 [email protected]
https://www.debian.org/lts/security/ Andrej Shadura
July 31, 2026 https://wiki.debian.org/LTS
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Package : python-authlib
Version : 0.15.4-1+deb11u4 1.2.0-1+deb12u2
CVE ID : CVE-2026-27962 CVE-2026-28490 CVE-2026-28498 CVE-2026-41425
CVE-2026-44681
The following security issue has been identified (and fixed) in python-authlib
as shipped in Debian bullseye and Debian bookworm.
CVE-2026-44681
An unauthenticated open redirect in Authlib's OpenIDImplicitGrant
and OpenIDHybridGrant authorisation endpoint allowed a remote
attacker to cause the authorisation server to issue an HTTP 302 to
an attacker-chosen URL by submitting an authorisation request that
omits the openid scope.
For Debian 11 bullseye, this problem has been fixed in version
0.15.4-1+deb11u4.
In addition, the following issues have been fixed in the python-authlib version
as shipped in Debian bookworm:
CVE-2026-27962
Fix authentication and authorization bypass vulnerability by embedding a
crafted public key in the jwk header field when key=None is passed to JWS
deserialisation functions.
CVE-2026-28490
Authlib exposed distinguishable error responses between invalid PKCS#1 v1.5
padding and invalid AES-GCM tag, enabling Bleichenbacher-style attacks.
CVE-2026-28498
Fix OIDC ID Token validation bypass in at_hash and c_hash verification.
_verify_hash() silently returned True when create_half_hash() received an
unknown algorithm, allowing forged ID Tokens to pass validation.
CVE-2026-41425
CSRF protection now covers the cache feature in
authlib.integrations.starlette_client.OAuth as well.
For Debian 12 bookworm, these problems have been fixed in version
1.2.0-1+deb12u2.
We recommend that you upgrade your python-authlib packages.
For the detailed security status of python-authlib please refer to
its security tracker page at:
https://security-tracker.debian.org/tracker/python-authlib
Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS
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