VULNERABILITY INTELLIGENCE

CVE-2017-11424

CVSS score7.5 HIGH

EPSS probability1.80%

CISA KEVNot currently listed

Published2017-08-24

Last modified2026-06-17

CVSS vectorCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

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.

Primary references

security@duo.com — Third Party Advisory
security@duo.com — Issue Tracking, Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108 — Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108 — Issue Tracking, Patch, Third Party Advisory