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.
Metrics
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NAffected software
No affected versions have been published.
Timeline
- Published
- Aug 24, 2017
- Last modified
- Jun 17, 2026
- NVD status
- Modified