CVE-2026-33996

MEDIUM

LibJWT has NULL/bounds validation in JWK octet and RSA PSS parsing

Title source: cna
STIX 2.1

Description

LibJWT is a C JSON Web Token Library. Starting in version 3.0.0 and prior to version 3.3.0, the JWK parsing for RSA-PSS did not protect against a NULL value when expecting to parse JSON string values. A specially crafted JWK file could exploit this behavior by using integers in places where the code expected a string. This was fixed in v3.3.0. A workaround is available. Users importing keys through a JWK file should not do so from untrusted sources. Use the `jwk2key` tool to check for validity of a JWK file. Likewise, if possible, do not use JWK files with RSA-PSS keys.

Scores

CVSS v3 5.5
EPSS 0.0001
EPSS Percentile 2.5%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-476
Status published
Products (2)
benmcollins/libjwt >= 3.0.0, < 3.3.0
libjwt/libjwt 3.0.0 - 3.3.0
Published Mar 27, 2026
Tracked Since Mar 29, 2026