SEPTEMBER 19, 2026
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Case File

CVE-2026-66046

HIGH · CVSS 7.5 EPSS 0.59% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-08-18 · Last synced 2026-09-17

CyberRota Analysis

AI-Generated

Expat versions up to 2.8.3 are vulnerable to a denial of service attack due to a quadratic algorithmic complexity in the storeAtts() function, which can lead to excessive CPU consumption when processing XML documents with non-normalized attribute values. A remote, unauthenticated attacker can exploit this vulnerability by submitting a specially crafted XML document, potentially disrupting service availability. Organizations utilizing Expat for XML parsing should prioritize patching or mitigating this vulnerability to prevent potential service outages.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-66046
Severity
HIGH
CVSS
7.5
EPSS
0.59%

Original NVD Description

Expat through 2.8.3 contains a denial of service vulnerability caused by quadratic algorithmic complexity in the storeAtts() function in xmlparse.c, where processing N specified attributes with non-normalized values triggers an O(N^2) linear scan of elementType->defaultAtts to determine CDATA status. A remote unauthenticated attacker can supply a single well-formed XML document of a few megabytes to an application parsing untrusted XML to cause excessive CPU consumption, resulting in denial of service without requiring authentication, external entity resolution, or non-default parser options.