CVE Catalog

CVE-2026-34240

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.13%

3th percentile - higher than 3% of all known CVEs

Summary

The JOSE library before version 0.3.5+1 allows an unauthenticated remote attacker to forge JWS/JWT tokens by using a key embedded in the JOSE header (jwk). The library incorrectly treats header-provided keys as verification candidates even when not in the trusted key store.

Risk Assessment

The risk is token forgery, potentially leading to unauthorized access to systems relying on JOSE for token verification.

Recommendation

Immediately update the JOSE library to version 0.3.5+1 or later. As a workaround, reject tokens with a jwk header unless the key matches a trusted key.

Related vulnerabilities

Original NVD description (English source)

JOSE is a Javascript Object Signing and Encryption (JOSE) library. Prior to version 0.3.5+1, a vulnerability in jose could allow an unauthenticated, remote attacker to forge valid JWS/JWT tokens by using a key embedded in the JOSE header (jwk). The vulnerability exists because key selection could treat header-provided jwk as a verification candidate even when that key was not present in the trusted key store. Since JOSE headers are untrusted input, an attacker could exploit this by creating a token payload, embedding an attacker-controlled public key in the header, and signing with the matching private key. Applications using affected versions for token verification are impacted. This issue has been patched in version 0.3.5+1. A workaround for this issue involves rejecting tokens where header jwk is present unless that jwk matches a key already present in the application's trusted key store.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS