CVE-2017-11424

Publication date 24 August 2017

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
pyjwt	17.04 zesty	Fixed 1.4.2-1ubuntu0.1
	16.04 LTS xenial	Fixed 1.3.0-1ubuntu0.1
	14.04 LTS trusty	Not in release

Notes

tyhicks

The added deprecation warnings present in the fix probably aren't needed in security backports

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
pyjwt	Upstream: https://github.com/jpadilla/pyjwt/pull/277

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	High
Availability impact	None
Vector	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N