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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Hsiaoming | Joserfc | <= 1.6.2 |
Related Weaknesses (CWE)
References
- https://github.com/authlib/joserfc/commit/696a9611ab982c45ee2190ed79ca8e1d8e0939Patch
- https://github.com/authlib/joserfc/security/advisories/GHSA-w5r5-m38g-f9f9ExploitMitigationVendor Advisory
FAQ
What is CVE-2026-27932?
CVE-2026-27932 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 ...
How severe is CVE-2026-27932?
CVE-2026-27932 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-27932?
Check the references section above for vendor advisories and patch information. Affected products include: Hsiaoming Joserfc.