CVE-2026-33996 MEDIUM

CVE-2026-33996: LibJWT has NULL/bounds validation in JWK octet and RSA PSS parsing

Vendor Benmcollins
Product libjwt
Weakness CWE-476
Published March 27, 2026
Last update March 31, 2026

CVSS base score

5.8/10
Attack vector Adjacent
Attack complexity High
Privileges required None
User interaction
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:A/VC:L/VI:L/VA:H/SC:L/SI:L/SA:L

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

March 27, 2026 CVE published
March 31, 2026 Record updated