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Vulnerability details

CVE-2026-102946

authlib joserfc

joserfc: JWS signature verification bypass via empty signatures array in jws.deserialize_json

CVSS 3.1
9.1Critical

Official description

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.7.4, joserfc.jws.deserialize_json() accepts a JWS General JSON Serialization with an empty signatures array as authenticated. The verify_general_json() loop performs no iterations for the empty array and returns success because no signature check failed, allowing an attacker without a signing key to supply an arbitrary payload that relying applications may treat as authentic. The issue affects the General JSON Serialization path; compact JWS and JWT decoding, Flattened JSON serialization, and JWE JSON processing do not follow this vulnerable path. This issue is fixed in version 1.7.4.

CVSS scores

ScoreVersionSourceVector
9.1Critical 3.1 CVEProject cvelistV5 (CNA) (GitHub_M) CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

VendorProductVersionsSource
authlib joserfc < 1.7.4 CVEProject cvelistV5 (CNA)

References and advisories

3
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Details

Published
2026-10-15
Last updated
2026-10-15
State
Published
Assigner (CNA)
GitHub_M
Kolun priority
14 · Low

Exploit prediction (EPSS)

0.11%
Probability of exploitation in 30 days
1.6%
Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable
Yes
Exploitation
Proof of concept
Technical impact
Total

Weaknesses (CWE)

  • CWE-290
    Authentication Bypass by Spoofing
  • CWE-345
    Insufficient Verification of Data Authenticity
  • CWE-347
    Improper Verification of Cryptographic Signature