Resource exhaustion in authlib - CVE-2025-62706
Published: October 31, 2025
Vulnerability identifier: #VU117880
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2025-62706
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Authlib
Affected software:
authlib
authlib
Detailed vulnerability description
The vulnerability allows a remote user to perform a denial of service (DoS) attack.
The vulnerability exists due to Authlib's JWE zip=DEF path performs unbounded DEFLATE decompression. A very small ciphertext can expand into tens or hundreds of megabytes on decrypt. A remote user can supply decryptable tokens and exhaust memory and CPU resources, leading to denial of service conditions.
How to mitigate CVE-2025-62706
Install updates from vendor's website.