{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "0"
              },
              {
                "last_affected": "\u003c 0.3.5+1"
              }
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "5a8511ab1f71b7a892a930b35a402d3b19d96f72"
            }
          ],
          "repo": "https://github.com/appsup-dart/jose",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-vm9r-h74p-hg97"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-347"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34240.json"
  },
  "details": "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.",
  "id": "CVE-2026-34240",
  "modified": "2026-04-01T23:07:53.983751295Z",
  "published": "2026-03-31T15:44:23.578Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34240.json"
    },
    {
      "type": "FIX",
      "url": "https://github.com/appsup-dart/jose/commit/b07799aac1f56a9a21483feac026272aab30cc5d"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/appsup-dart/jose/security/advisories/GHSA-vm9r-h74p-hg97"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34240"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "jose vulnerable to untrusted JWK header key acceptance during signature verification"
}