CVE-2017-11424
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.80%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.0
- 7.5 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- EPSS
- 1.80% probability · 77th percentile
- CISA KEV
- Not listed
- Affected
- pyjwt project/pyjwt · debian/debian linux
- Source
- security@duo.com
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.