Bug 2452531 (CVE-2026-33996)

Summary: CVE-2026-33996 LibJWT: LibJWT: Denial of Service via crafted JSON Web Key (JWK) files
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in LibJWT, a C JSON Web Token Library. When parsing JSON Web Key (JWK) files for RSA-PSS, the library did not correctly handle cases where NULL values were encountered instead of expected string values. An attacker could exploit this vulnerability by providing a specially crafted JWK file containing integers in fields that anticipate strings. This could lead to a denial of service, impacting the availability of systems using the affected library.
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Description OSIDB Bzimport 2026-03-27 23:01:49 UTC 
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.