CVE-2026-102946: Signature Bypass (CVSS 9.1)

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.

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CVSS v3.1 Score

9.1

CRITICAL

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

Weakness Type (CWE)

CWE-290 CWE-290

CWE-345 CWE-345

CWE-347 CWE-347

References

Other 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

Frequently Asked Questions

What is CVE-2026-102946? +

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. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2026-102946? +

CVE-2026-102946 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

How do I check if I'm vulnerable to CVE-2026-102946? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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