{"id":"CVE-2017-11424","url":"https://www.cyber-defence.io/tools/cve/CVE-2017-11424","generatedAt":"2026-10-28T20:12:41.738Z","title":"Specifically, the PKCS1 PEM encoded format would be allowed because it is prefaced with the string `-----BEGIN RSA PUBLIC KEY-----` which is not accounted for.","description":"In PyJWT 1.5.0 and below the `invalid_strings` check in `HMACAlgorithm.prepare_key` does not account for all PEM encoded public keys. Specifically, the PKCS1 PEM encoded format would be allowed because it is prefaced with the string `-----BEGIN RSA PUBLIC KEY-----` which is not accounted for. This enables symmetric/asymmetric key confusion attacks against users using the PKCS1 PEM encoded public keys, which would allow an attacker to craft JWTs from scratch.","published":"2017-08-24T16:29:00.000Z","lastModified":"2026-06-17T01:01:48.000Z","status":"Modified","sourceIdentifier":"security@duo.com","cvss":{"version":"3.0","score":7.5,"severity":"HIGH","vector":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"},"cwe":[],"affected":["pyjwt project/pyjwt","debian/debian linux"],"epss":{"score":0.01804,"percentile":0.78434,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (1.80%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"http://www.debian.org/security/2017/dsa-3979","tags":["Third Party Advisory"],"source":"security@duo.com"},{"url":"https://github.com/jpadilla/pyjwt/pull/277","tags":["Issue Tracking","Patch","Third Party Advisory"],"source":"security@duo.com"},{"url":"http://www.debian.org/security/2017/dsa-3979","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/jpadilla/pyjwt/pull/277","tags":["Issue Tracking","Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2017-11424","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}