CVE-2017-11424

Name: CVE-2017-11424
Creator: NVD / NIST
Published: 2017-08-24T16:29:00.197+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 1.80%

Last modified Jun 17, 2026

CVE-2017-11424 is a vulnerability of currently unknown severity. 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. EPSS estimates a 1.80% chance of exploitation in the next 30 days.

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

EPSS Probability

1.80%

75.8th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Vendor	Product	Versions
Pyjwt Project	Pyjwt	<= 1.5.0
Debian	Debian Linux	8.0
Debian	Debian Linux	9.0

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
Status: Modified

Frequently Asked Questions

What is CVE-2017-11424?

How severe is CVE-2017-11424?

Severity scoring for CVE-2017-11424 is pending analysis. The EPSS model estimates a 1.80% probability of exploitation in the next 30 days.

How do I fix CVE-2017-11424?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2017-11424?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST