{"id":"CVE-2026-34240","title":"JOSE is a Javascript Object Signing and Encryption (JOSE) library","summary":"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…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","cwe":["CWE-347"],"vendor":"appsup-dart","product":"jose","affected":["jose < 0.3.5\\+1"],"patched":["jose 0.3.5\\+1"],"published":"2026-03-31","updated":"2026-07-24","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-34240","references":[{"url":"https://github.com/appsup-dart/jose/commit/b07799aac1f56a9a21483feac026272aab30cc5d","label":"security-advisories@github.com"},{"url":"https://github.com/appsup-dart/jose/security/advisories/GHSA-vm9r-h74p-hg97","label":"security-advisories@github.com"}],"tags":["nvd"],"epss":0.0013,"epssPercentile":0.02991,"ingestedAt":"2026-07-24T20:38:02.494Z","slug":"CVE-2026-34240","body":"## Overview\n\nJOSE 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.\n\n## Affected\n\n- `jose < 0.3.5\\+1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `jose 0.3.5\\+1`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}