PT-2026-29287 · Appsup Dart · Jose

Published 2026-03-31 · Updated 2026-03-31 · CVE-2026-34240

NVD

CVSS v3.1

7.5

High

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

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.

Fix

Improper Verification of Cryptographic Signature

Weakness Enumeration

CWE-347

Related Identifiers

CVE-2026-34240

Affected Products

Jose

References · 3

• https://nvd.nist.gov/vuln/detail/CVE-2026-34240 · Security Note
• https://github.com/appsup-dart/jose/security/advisories/GHSA-vm9r-h74p-hg97 · Note
• https://github.com/appsup-dart/jose/commit/b07799aac1f56a9a21483feac026272aab30cc5d · Note