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

Exp

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.

Published: 2026-03-03 Last update: 2026-03-05 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-27932 is rated Exploit Available (50/100): CVSS High severity, with low exploitation likelihood (EPSS 0.05%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-27932

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-27932

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-21 0.16% 0.05% -0.11%
2 2026-04-14 0.08% 0.16% +0.08%
3 2026-03-06 — 0.08% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-27932

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-27932

GitHub Security Advisory for CVE-2026-27932

GHSA-w5r5-m38g-f9f9 · Severity: high · Ecosystem: pip — joserfc's PBES2 p2c Unbounded Iteration Count enables Denial of Service (DoS)

OS Trackers for CVE-2026-27932

vendor priority summary link
debian not yet assigned CVE-2026-27932 not yet assigned priority: Debian including 1 source packages (joserfc), 3 status rows across 3 suites (forky, sid, trixie): resolved 2, open 1. https://security-tracker.debian.org/tracker/CVE-2026-27932
ubuntu medium CVE-2026-27932 medium priority: Ubuntu including 1 source packages (joserfc), 4 status rows across 4 suites (jammy, noble, questing, upstream): DNE 2, needs-triage 1, released 1. https://ubuntu.com/security/CVE-2026-27932

Affected software / configurations for CVE-2026-27932

Vendor Product Version Raw CPE
hsiaoming joserfc <= 1.6.2 cpe:2.3:a:hsiaoming:joserfc:*:*:*:*:*:python:*:*

References for CVE-2026-27932

cvelogic Threat Intelligence