Bug 2444248 (CVE-2026-27932)

Summary:	CVE-2026-27932 joserfc: joserfc: Denial of Service via unbounded PBKDF2 iteration count in JWE decryption
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	caswilli, kaycoth
Target Milestone:	---	Keywords:	Security
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Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in joserfc, a Python library for JSON Object Signing and Encryption (JOSE) standards. An unauthenticated attacker can cause a Denial of Service (DoS) by exploiting a resource exhaustion vulnerability. This occurs when the library decrypts a JSON Web Encryption (JWE) token using Password-Based Encryption (PBES2) algorithms, as it reads the p2c (PBES2 Count) parameter directly from the token's protected header without validation. An attacker can specify an extremely large iteration count for the PBKDF2 key derivation function, forcing the server to expend massive CPU resources processing a single token, leading to CPU exhaustion and a Denial of Service.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description OSIDB Bzimport 2026-03-03 23:02:45 UTC

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In 1.6.2 and earlier, a resource exhaustion vulnerability in joserfc allows an unauthenticated attacker to cause a Denial of Service (DoS) via CPU exhaustion. When the library decrypts a JSON Web Encryption (JWE) token using Password-Based Encryption (PBES2) algorithms, it reads the p2c (PBES2 Count) parameter directly from the token's protected header. This parameter defines the number of iterations for the PBKDF2 key derivation function. Because joserfc does not validate or bound this value, an attacker can specify an extremely large iteration count (e.g., 2^31 - 1), forcing the server to expend massive CPU resources processing a single token. This vulnerability exists at the JWA layer and impacts all high-level JWE and JWT decryption interfaces if PBES2 algorithms are allowed by the application's policy.