CVE-2026-27932— joserfc PBES2 p2c Unbounded Iteration Count enables Denial of Service (DoS)

joserfc PBES2 p2c Unbounded Iteration Count enables Denial of Service (DoS)

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

不加限制或调节的资源分配

joserfc 安全漏洞

joserfc是Authlib开源的一个Python库。 joserfc 1.6.2及之前版本存在安全漏洞，该漏洞源于未验证或限制JWE令牌中p2c参数值，可能导致未经验证的攻击者通过CPU耗尽造成拒绝服务。

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