SecuriTricks - CVE-2025-61920

Description

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to version 1.6.5, Authlib’s JOSE implementation accepts unbounded JWS/JWT header and signature segments. A remote attacker can craft a token whose base64url‑encoded header or signature spans hundreds of megabytes. During verification, Authlib decodes and parses the full input before it is rejected, driving CPU and memory consumption to hostile levels and enabling denial of service. Version 1.6.5 patches the issue. Some temporary workarounds are available. Enforce input size limits before handing tokens to Authlib and/or use application-level throttling to reduce amplification risk.

Product(s) Impacted

Vendor	Product	Versions
Authlib	Authlib	<1.6.5

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-20

Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

*CPE(s)

Affected systems and software identified for this CVE.

Type	Vendor	Product	Version	Update	Edition	Language	Software Edition	Target Software	Target Hardware	Other Information
a	authlib	authlib	<1.6.5	/	/	/	/	/	/	/

References

https://github.com/authlib/authlib/commit/867e3f87b072347a1ae9cf6983cc8bbf88447e5e

https://github.com/authlib/authlib/security/advisories/GHSA-pq5p-34cr-23v9

CVSS Score

7.5 / 10

CVSS Data - 3.1

Attack Vector: NETWORK
Attack Complexity: LOW
Privileges Required: NONE
Scope: UNCHANGED
Confidentiality Impact: NONE
Integrity Impact: NONE
Availability Impact: HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

View Vector String

Timeline

Published: Oct. 10, 2025, 8:15 p.m.
Last Modified: Oct. 10, 2025, 8:15 p.m.

Status : Received

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

security-advisories@github.com

CVE-2025-61920