Medium severity · published Sep 28, 2026
CVE-2026-102265
PyJWT: Uncaught RecursionError in jwt.decode() on deeply nested token header
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWS._load in jwt/api_jws.py is affected because parser catches ValueError but not RecursionError. This occurs when a deeply nested token header reaches json.loads. As a result, RecursionError escapes the documented PyJWT error hierarchy. Consequently, an unauthenticated malformed token can cause a request-level failure and HTTP 500. This issue is fixed in version 2.14.0.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 28% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PY
pyjwt · jpadilla
>= 2.13.0, < 2.14.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-102265
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-102265
x_refsource_CONFIRM
https://github.com/jpadilla/pyjwt/security/advisories/GHSA-8wjv-2p76-3863
x_refsource_MISC
https://github.com/jpadilla/pyjwt/commit/06573692ebcdec8831c3927513b3e87c31fbbb62
x_refsource_MISC
https://github.com/jpadilla/pyjwt/releases/tag/2.14.0
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