Resource exhaustion in authlib - CVE-2025-61920
Published: October 31, 2025
Vulnerability identifier: #VU117881
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2025-61920
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to the way the Authlib's JOSE implementation handles untrusted input. A remote non-authenticated attacker can send overly large amount of data via unbounded JWS/JWT header and signature segments to the application and consume memory and CPU resources, leading to a denial of service condition.
Affected software
authlib
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Server 15
Python 3 Module
openSUSE Leap
Ubuntu
Quay
python-authlib (Ubuntu package)
python311-Authlib
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Server 15
Python 3 Module
openSUSE Leap
Ubuntu
Quay
python-authlib (Ubuntu package)
python311-Authlib
How to mitigate CVE-2025-61920
Install updates from vendor's website.
authlib - update to 1.6.5
Quay - addressed in versions 3.9.0, 3.12.0, 3.13.10
python-authlib (Ubuntu package) - addressed in versions 0.15.5-1ubuntu0.1~esm1, 1.3.0-1ubuntu0.1~esm1
python311-Authlib - update to 1.3.1-150600.3.6.1
Quay - addressed in versions 3.9.0, 3.12.0, 3.13.10
python-authlib (Ubuntu package) - addressed in versions 0.15.5-1ubuntu0.1~esm1, 1.3.0-1ubuntu0.1~esm1
python311-Authlib - update to 1.3.1-150600.3.6.1