### [CVE-2017-11424](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-11424)
![](https://img.shields.io/static/v1?label=Product&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Version&message=n%2Fa&color=blue)
![](https://img.shields.io/static/v1?label=Vulnerability&message=n%2Fa&color=brighgreen)

### 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.

### POC

#### Reference
No PoCs from references.

#### Github
- https://github.com/CompassSecurity/security_resources
- https://github.com/aymankhder/security_resources
- https://github.com/silentsignal/rsa_sign2n