CVE-2017-11424 PyJWT vulnerable to key confusion attacks

What is CVE-2017-11424?

CVE-2017-11424 is a high-severity vulnerability in Debian Debian Linux, published on 24 Aug 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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.

Which versions are affected by CVE-2017-11424?

3 open source packages ship an affected version, including pyjwt. It affects 2 products.

Products include Debian Debian Linux, Pyjwt Project Pyjwt.

How do I fix CVE-2017-11424?

Upgrade pyjwt to 1.5.1 or later.

Is CVE-2017-11424 being exploited?

There is no known exploitation of CVE-2017-11424 in the wild and no public exploit code.

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All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as CVE-2017-12880, DEBIAN-CVE-2017-11424, DSA-3979-1, GHSA-r9jw-mwhq-wp62, PYSEC-2017-24, UBUNTU-CVE-2017-11424 and 1 more.