Critical 9.1Published Oct 15, 2026

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

Updated under an hour ago (2026-10-19 05:50 UTC)

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It affects authlib joserfc. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.12%, higher than 2% of scored CVEs.

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Every CVE for authlib joserfc

Exploited in the last 30 days

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: 9.1 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE): CWE-290, CWE-345, CWE-347
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.12% (percentile 2)
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Oct 15, 2026
First seen by InfoSec Signals: Oct 15, 2026

Affected products

Affected products

authlib joserfc authlib:joserfc (from the name)	before 1.7.4	CNA record

References

https://github.com/authlib/joserfc/security/advisories/GHSA-4pp3-559j-c5c2x-refsource-confirm
https://github.com/authlib/joserfc/commit/f409f8f058225d7686acab6546c94593e4c1bfbex-refsource-misc
https://github.com/authlib/joserfc/releases/tag/1.7.4x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.