Log in Start free

Vulnerability · Published Oct 28, 2026 · Assigned by VulnCheck

CVE-2026-118370libexpat through 2.9.0 Integer Overflow in storeAtts via attIndex and nPrefixes

Medium 5.9

In plain English

A medium-severity integer overflow in libexpat from libexpat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 33% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.9Medium
Exploit odds (30 days)0.4%top 66.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.21expat2.10.0-r0ALPINE-CVE-2026-118370
Alpine:v3.22expat2.10.0-r0ALPINE-CVE-2026-118370
Alpine:v3.23expat2.10.0-r0ALPINE-CVE-2026-118370
Alpine:v3.24expat2.10.0-r0ALPINE-CVE-2026-118370
Debian:12expatno fix listedDEBIAN-CVE-2026-118370
Debian:13expatno fix listedDEBIAN-CVE-2026-118370
Debian:14expatno fix listedDEBIAN-CVE-2026-118370
Ubuntu:22.04:LTScadaverno fix listedUBUNTU-CVE-2026-118370
Ubuntu:24.04:LTScadaverno fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.04:LTScadaverno fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.10cadaverno fix listedUBUNTU-CVE-2026-118370
Ubuntu:22.04:LTSexpatno fix listedUBUNTU-CVE-2026-118370
Ubuntu:24.04:LTSexpatno fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.04:LTSexpatno fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.10expatno fix listedUBUNTU-CVE-2026-118370
Ubuntu:22.04:LTSinsighttoolkit4no fix listedUBUNTU-CVE-2026-118370
Ubuntu:22.04:LTSmatanzano fix listedUBUNTU-CVE-2026-118370
Ubuntu:24.04:LTSmatanzano fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.04:LTSmatanzano fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.10matanzano fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.10swish-eno fix listedUBUNTU-CVE-2026-118370
Ubuntu:22.04:LTStdomno fix listedUBUNTU-CVE-2026-118370
Ubuntu:24.04:LTStdomno fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.04:LTStdomno fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.10tdomno fix listedUBUNTU-CVE-2026-118370
Ubuntu:22.04:LTSwbxml2no fix listedUBUNTU-CVE-2026-118370
Ubuntu:24.04:LTSwbxml2no fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.04:LTSwbxml2no fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.10wbxml2no fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.04:LTSxmlrpc-cno fix listedUBUNTU-CVE-2026-118370
Ubuntu:26.10xmlrpc-cno fix listedUBUNTU-CVE-2026-118370

Affected products (as reported)

VendorProductVersions
libexpat libexpat 0 – through 2.9.0

Weakness: CWE-190 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References