Description

pyjwt is a JSON Web Token implementation in Python. An incorrect string comparison is run for `iss` checking, resulting in `"acb"` being accepted for `"_abc_"`. This is a bug introduced in version 2.10.0: checking the "iss" claim changed from `isinstance(issuer, list)` to `isinstance(issuer, Sequence)`. Since str is a Sequnce, but not a list, `in` is also used for string comparison. This results in `if "abc" not in "__abcd__":` being checked instead of `if "abc" != "__abc__":`. Signature checks are still present so real world impact is likely limited to denial of service scenarios. This issue has been patched in version 2.10.1. All users are advised to upgrade. There are no known workarounds for this vulnerability.

Classification

CVE ID: CVE-2024-53861

CVSS Base Severity: LOW

CVSS Base Score: 2.2

Affected Products

Vendor: jpadilla

Product: pyjwt

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.06% (probability of being exploited)

EPSS Percentile: 30.39% (scored less or equal to compared to others)

EPSS Date: 2025-02-03 (when was this score calculated)

References

https://github.com/jpadilla/pyjwt/security/advisories/GHSA-75c5-xw7c-p5pm
https://github.com/jpadilla/pyjwt/commit/1570e708672aa9036bc772476beae8bfa48f4131#diff-6893ad4a1c5a36b8af3028db8c8bc3b62418149843fc382faf901eaab008e380R366
https://github.com/jpadilla/pyjwt/commit/33022c25525c1020869c71ce2a4109e44ae4ced1

Timeline