CVE-2026-27932
joserfc's PBES2 p2c Unbounded Iteration Count enables Denial of Service (DoS)
描述
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.
如何修補 CVE-2026-27932
要修補 CVE-2026-27932,請將受影響套件升級到下列已修補版本。
- —未列出修補版本
- —升級至 1.6.3 或更新版本
CVE-2026-27932 正在被利用嗎?
低 — EPSS 為 0.0%,目前沒有觀察到大規模利用活動。
受影響套件(2)
- from 0
- from 0, < 1.6.3
CVSS 分數
| 來源 | 版本 | 嚴重程度 | 向量 |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |