What is CVE-2026-102946?

CVE-2026-102946 is a critical-severity vulnerability in Authlib Joserfc, classified under Authentication Bypass by Spoofing. CVSS score: 9.1/10. Published 2026-10-15.

How severe is CVE-2026-102946?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Authlib Joserfc

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.

Published 2026-10-15 · last modified 2026-10-15.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Authlib Joserfc — versions < 1.7.4

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-102946?: CVE-2026-102946 is a critical-severity vulnerability in Authlib Joserfc, classified under Authentication Bypass by Spoofing. CVSS score: 9.1/10. Published 2026-10-15.
How severe is CVE-2026-102946?: Critical severity. CVSS v3 base score is 9.1 out of 10.