Dashboard / CVE-2026-66046

CVE-2026-66046

HIGH
MEDIUM Priority: 0.06 BB Relevance: 78/100
Published: 2026-08-18 Modified: 2026-10-22 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Auth No Interaction

CVSS Vector Breakdown

AV: Network
AC: Low
PR: None
UI: None
S: X
AT: None
VC: None
VI: None
VA: High

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.

Weakness Classification (1)

Affected Software (1)

VendorProductVersion
libexpat_project libexpat < 2.8.3

References & Advisories (2)

https://github.com/libexpat/libexpat/pull/1321
Exploit Patch Vendor Advisory

Bug Bounty Relevance

78 / 100
✓ Network accessible
✓ No authentication
✓ Low complexity
✓ No user interaction

CVSS Score

8.7 / 10.0 v4.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — Exploitation Probability

0.74%
Raw Score 0.007420
Percentile 54.6%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00742
2026-10-28
0.00742

Intelligence Sources

nvd ref →

External Links