CVE-2017-11424 Affecting pyjwt package, versions <1.3.0-1ubuntu0.1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
1.3% (79th percentile)

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  • Snyk IDSNYK-UBUNTU1604-PYJWT-270904
  • published24 Aug 2017
  • disclosed24 Aug 2017

Introduced: 24 Aug 2017

CVE-2017-11424  (opens in a new tab)

How to fix?

Upgrade Ubuntu:16.04 pyjwt to version 1.3.0-1ubuntu0.1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream pyjwt package and not the pyjwt package as distributed by Ubuntu. See How to fix? for Ubuntu:16.04 relevant fixed versions and status.

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.