Vulnerability · Published Nov 29, 2024 · Assigned by GitHub_M

CVE-2024-53861Issuer field partial matches allowed in pyjwt

Low 2.2

In plain English

A low-severity security flaw in pyjwt from jpadilla. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 58% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)2.2Low

Exploit odds (30 days)0.8%top 42.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	pyjwt	2.10.1	GHSA-75c5-xw7c-p5pm
PyPI	pyjwt	2.10.1	PYSEC-2026-1814

Affected products (as reported)

Vendor	Product	Versions
jpadilla	pyjwt	= 2.10.0

Weakness: CWE-697 · Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:N

References

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