All vulnerabilities
CVE-2026-102946GHSA-4pp3-559j-c5c2

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

authlib joserfc
Open in ThreatlineRecord JSON
CVSS
9.1Critical
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 15 Oct 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.12%Chance of exploitation activity in the next 30 days, higher than 1% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in1.7.4Fixed versionGitHub
Published15 Oct 2026Updated 15 Oct 2026CVE List

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

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.

Text from CVE List

Affected versions 2

  • joserfcaffected: < 1.7.4CVE List
  • joserfc, pip1.7.3GitHub

References 3