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

Quick assessment

Affected
authlib joserfc
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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。

CVSS 7.5 · High EPSS 0.35% · P26
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I. Basic Information for CVE-2026-27932

Vulnerability Information
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Vulnerability Title
joserfc PBES2 p2c Unbounded Iteration Count enables Denial of Service (DoS)
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
joserfc 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
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。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
authlib joserfc <= 1.6.2 -

II. Public POCs for CVE-2026-27932

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 8071 chars
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III. Intelligence Information for CVE-2026-27932

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Patches & Fixes for CVE-2026-27932 (1)

Vendor Advisories for CVE-2026-27932 (1)

IV. Related Vulnerabilities

Same product: joserfc
Same vendor: authlib
Same weakness: CWE-770

V. Comments for CVE-2026-27932

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