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 7.5/10
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:NAffected software
| Vendor | Product | Versions |
|---|---|---|
| n/a | n/a | n/a |
References
- http://www.debian.org/security/2017/dsa-3979Third Party Advisory
- https://github.com/jpadilla/pyjwt/pull/277Issue Tracking, Patch, Third Party Advisory
- http://www.debian.org/security/2017/dsa-3979Third Party Advisory
- https://github.com/jpadilla/pyjwt/pull/277Issue Tracking, Patch, Third Party Advisory
Timeline
- Published
- Aug 24, 2017
- Last modified
- Jun 17, 2026
- NVD status
- Modified