What’s Vulnerable › Vulnerabilities

CVE-2026-102946: joserfc: JWS signature verification bypass via empty signatures array in jws.deserialize_json

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-15 · updated 2026-10-15
• Weakness: CWE-290

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.

Affected products

• authlib joserfc: before 1.7.4

References

• https://github.com/authlib/joserfc/commit/f409f8f058225d7686acab6546c94593e4c1bfbe
• https://github.com/authlib/joserfc/releases/tag/1.7.4
• https://github.com/authlib/joserfc/security/advisories/GHSA-4pp3-559j-c5c2
• https://github.com/authlib/joserfc/security/advisories/GHSA-4pp3-559j-c5c2

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