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.
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History
Wed, 04 Mar 2026 22:15:00 +0000
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ssvc
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Wed, 04 Mar 2026 15:00:00 +0000
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Authlib
Authlib joserfc |
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Authlib
Authlib joserfc |
Tue, 03 Mar 2026 23:00:00 +0000
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| 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. | |
| Title | joserfc PBES2 p2c Unbounded Iteration Count enables Denial of Service (DoS) | |
| Weaknesses | CWE-770 | |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2026-03-03T22:48:21.306Z
Updated: 2026-03-04T21:20:55.097Z
Reserved: 2026-02-25T03:11:36.688Z
Link: CVE-2026-27932
Updated: 2026-03-04T21:20:50.283Z
Status : Awaiting Analysis
Published: 2026-03-03T23:15:56.050
Modified: 2026-03-04T18:08:05.730
Link: CVE-2026-27932
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