CVE-2017-11424

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.

7.5

CVSS

Severity: High

CVSS 3.0 •

CVSS 2.0 •

EPSS 1.30% Top 25%

Vendor Advisory debian.org

Affected: n/a n/a

References

Link	Tags
http://www.debian.org/security/2017/dsa-3979	third party advisory vendor advisory
https://github.com/jpadilla/pyjwt/pull/277	patch third party advisory issue tracking

Frequently Asked Questions

What is the severity of CVE-2017-11424?: CVE-2017-11424 has been scored as a high severity vulnerability.
How to fix CVE-2017-11424?: To fix CVE-2017-11424, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2017-11424 being actively exploited in the wild?: It is possible that CVE-2017-11424 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~1% probability that this vulnerability will be exploited by malicious actors in the next 30 days.

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