libexpat through 2.9.0 contains a signed integer overflow vulnerability in storeAtts() in lib/xmlparse.c that allows attackers to trigger out-of-bounds writes via oversized attribute counts. Attackers can supply a multi-gigabyte document with a start tag carrying over 2^30 attributes to overflow attIndex and nPrefixes, crashing applications or corrupting heap memory.

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Wed, 28 Oct 2026 02:30:00 +0000

Type Values Removed Values Added
Description libexpat through 2.9.0 contains a signed integer overflow vulnerability in storeAtts() in lib/xmlparse.c that allows attackers to trigger out-of-bounds writes via oversized attribute counts. Attackers can supply a multi-gigabyte document with a start tag carrying over 2^30 attributes to overflow attIndex and nPrefixes, crashing applications or corrupting heap memory.
Title libexpat through 2.9.0 Integer Overflow in storeAtts via attIndex and nPrefixes
First Time appeared Libexpat Project
Libexpat Project libexpat
Weaknesses CWE-190
CPEs cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*
Vendors & Products Libexpat Project
Libexpat Project libexpat
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.2, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-28T02:03:19.447Z

Reserved: 2026-10-28T01:19:19.454Z

Link: CVE-2026-118370

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-10-28T03:17:13.293

Modified: 2026-10-28T15:21:31.673

Link: CVE-2026-118370

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-28T06:45:14Z

Weaknesses