CVE-2026-27932: fallo de gravedad alta en authlib joserfc
joserfc PBES2 p2c Unbounded Iteration Count enables Denial of Service (DoS)
Publicada el · Actualizada el
Aviso por correo cuando entre en el KEV, tenga PoC pública o suba de nota.
21Vexday Risk Score
Sin señal de explotación. Ningún artefacto público de explotación conocido hasta ahora.
ssvc Trackcvss 7.5epss 0.5%
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
Productos afectados
authlib · joserfcCVEs relacionadas — authlib joserfc
En el mismo producto, de las más peligrosas a las menos.
CVE-2025-65015CRITICALjoserfc has Possible Uncontrolled Resource Consumption Vulnerability Triggered by Logging Arbitrarily Large JWT Token PayloadsEPSS 0.4%CVE-2026-48990MEDIUMjoserfc: b64=false RFC7797 JWS payloads bypass JWSRegistry payload-size limits during deserializationEPSS 0.2%CVE-2026-119283HIGHjoserfc: Unbounded JWE General JSON `recipients` Array Leads to CPU Exhaustion (DoS) via Repeated RSA Private-Key DecryptionEPSS 0.2%CVE-2026-119284MEDIUMjoserfc: Compact JWS size guard allocates attacker-controlled segments before rejectionEPSS 0.2%CVE-2026-49852HIGHjoserfc: HS256/HS384/HS512 verify accepts empty/nil HMAC key (cross-language sibling of CVE-2026-45363)EPSS 0.2%CVE-2026-62995LOWjoserfc accepts JWT with padding, leading to JWT malleabilityEPSS 0.1%