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.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade pyjwt | Dec 4, 2017 | Aug 24, 2017 |
| Suse | — | Upgrade python3-pyjwt | Oct 20, 2017 | Aug 24, 2017 |
| Ubuntu | — | Upgrade python3-jwtUpgrade python-jwt | Aug 31, 2017 | Aug 24, 2017 |
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