CVE-2026-49852 | joserfc is a Python library that provides an implementation … | CVSS 8.7 HIGH

Description

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.6.8, joserfc.jwt.decode accepts attacker-forged HMAC-signed tokens when the caller-supplied verification key is the empty string or None, because HMACAlgorithm.sign and HMACAlgorithm.verify in src/joserfc/_rfc7518/jws_algs.py pass the output of OctKey.get_op_key(...) to hmac.new(...) and OctKey.import_key in src/joserfc/_rfc7518/oct_key.py only emits a SecurityWarning for keys shorter than 14 bytes without rejecting zero-length input. This issue is fixed in version 1.6.8.

Metadata

CVE ID: CVE-2026-49852
State: PUBLISHED
Assigner: GitHub_M
Reserved: 2026-06-01 22:03 UTC
Published: 2026-07-17 19:14 UTC
Last updated: 2026-07-17 19:14 UTC
Primary CWE: CWE-287
CWE-287: Improper Authentication
Vendor / Product: authlib / joserfc
Sources: cve.org · NVD

Severity & Metrics

8.7 HIGH CVSS 4.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Affected products (1)

Vendor	Product	Platform	Versions
authlib	joserfc	—	< 1.6.8

Weakness (CWE)

CWE	Source	Description
CWE-1391	cna	CWE-1391: Use of Weak Credentials
CWE-287	cna	CWE-287: Improper Authentication
CWE-326	cna	CWE-326: Inadequate Encryption Strength

CVSS scores (1)

Score	Severity	Version	Source	Vector
8.7	HIGH	4.0	cna	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

References (3)

https://github.com/authlib/joserfc/security/advisories/GHSA-gg9x-qcx2-xmrh https://github.com/authlib/joserfc/security/advisories/GHSA-gg9x-qcx2-xmrh
https://github.com/authlib/joserfc/commit/86d00910b2b2d2d07503fee9b572906daefab7f1 https://github.com/authlib/joserfc/commit/86d00910b2b2d2d07503fee9b572906daefab7f1
https://github.com/authlib/joserfc/releases/tag/1.6.8 https://github.com/authlib/joserfc/releases/tag/1.6.8