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Vulnerability · Published Sep 29, 2026 · Assigned by VulnCheck

CVE-2026-102633libexpat 2.7.2 through 2.8.5 Integer Overflow in expat_realloc

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 31% 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 69.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

libexpat versions 2.7.2 through 2.8.5 contain an integer overflow vulnerability in expat_realloc() function on 32-bit platforms when computing allocation sizes. Attackers supplying malicious XML to applications parsing with vulnerable libexpat can cause heap buffer overflow, memory corruption, or denial of service.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10expat2.7.3-1.el10_2.7ALSA-2026:88248
AlmaLinux:8expat2.5.0-6.el8_10ALSA-2026:92323
AlmaLinux:9expat2.5.0-6.el9_8.7ALSA-2026:88247
AlmaLinux:8expat-devel2.5.0-6.el8_10ALSA-2026:92323
AlmaLinux:9expat-devel2.5.0-6.el9_8.7ALSA-2026:88247
Alpine:v3.21expat2.9.0-r0ALPINE-CVE-2026-102633
Alpine:v3.22expat2.9.0-r0ALPINE-CVE-2026-102633
Alpine:v3.23expat2.9.0-r0ALPINE-CVE-2026-102633
Alpine:v3.24expat2.9.0-r0ALPINE-CVE-2026-102633
Debian:12expat2.5.0-1+deb12u5DEBIAN-CVE-2026-102633
Debian:13expat2.9.0-1~deb13u1DEBIAN-CVE-2026-102633
Debian:14expat2.8.5-2DEBIAN-CVE-2026-102633
Rocky Linux:10expat0:2.7.3-1.el10_2.7RLSA-2026:88248
Rocky Linux:8expat0:2.5.0-6.el8_10RLSA-2026:92323
Rocky Linux:9expat0:2.5.0-6.el9_8.7RLSA-2026:88247
Ubuntu:26.04:LTScadaverno fix listedUBUNTU-CVE-2026-102633
Ubuntu:26.10cadaverno fix listedUBUNTU-CVE-2026-102633
Ubuntu:24.04:LTSexpatno fix listedUBUNTU-CVE-2026-102633
Ubuntu:26.04:LTSexpatno fix listedUBUNTU-CVE-2026-102633
Ubuntu:26.10expatno fix listedUBUNTU-CVE-2026-102633
Ubuntu:22.04:LTSinsighttoolkit4no fix listedUBUNTU-CVE-2026-102633
Ubuntu:22.04:LTSmatanzano fix listedUBUNTU-CVE-2026-102633
Ubuntu:24.04:LTSmatanzano fix listedUBUNTU-CVE-2026-102633
Ubuntu:26.04:LTSmatanzano fix listedUBUNTU-CVE-2026-102633
Ubuntu:26.10matanzano fix listedUBUNTU-CVE-2026-102633
Ubuntu:26.10swish-eno fix listedUBUNTU-CVE-2026-102633
Ubuntu:26.10tdomno fix listedUBUNTU-CVE-2026-102633
Ubuntu:26.10wbxml2no fix listedUBUNTU-CVE-2026-102633
Ubuntu:26.10xmlrpc-cno fix listedUBUNTU-CVE-2026-102633

Affected products (as reported)

VendorProductVersions
libexpat libexpat 2.7.2 – through 2.8.5

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

References