Description
A flaw was found in the jwcrypto library, which is used for implementing Javascript Object Signing and Encryption (JOSE) standards. The issue occurs when the library verifies a General JSON Serialization JWS using a set of keys. Due to a coding error, the library fails to correctly identify the specific key ID (kid) and may instead accept a signature made by any valid key in the set. This can allow an attacker with a valid key to bypass authorization checks in applications that rely on the key ID to identify specific tenants or users.
References2
Metrics
- CVSS 3.1
-
5.9
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N - EPSS — exploit probability
- 0% percentile: 3 · as of 3 November 2026
- CWE
- CWE-347
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.