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PyJWT vulnerable to key confusion attacks

High severity GitHub Reviewed Published May 13, 2022 to the GitHub Advisory Database • Updated Oct 15, 2024

Package

pip pyjwt (pip)

Affected versions

< 1.5.1

Patched versions

1.5.1

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.

References

Published by the National Vulnerability Database Aug 24, 2017
Published to the GitHub Advisory Database May 13, 2022
Reviewed Sep 12, 2022
Last updated Oct 15, 2024

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS score

0.082%
(36th percentile)

Weaknesses

No CWEs

CVE ID

CVE-2017-11424

GHSA ID

GHSA-r9jw-mwhq-wp62

Source code

Credits

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