Out-of-bounds read in expat - CVE-2026-72522

Vulnerability identifier: #VU149951

CSH Severity: Medium

CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-72522

CWE-ID: CWE-125

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to a boundary condition during Unicode processing in the *_toUtf16 function. A remote attacker can pass specially crafted XML input to the application, trigger an infinite loop and perform a denial of service attack.

expat
Debian Linux
Ubuntu
openEuler
Fedora
xmlrpc-c
xmlrpc-c-debuginfo
xmlrpc-c-debugsource
xmlrpc-c-help
xmlrpc-c-devel
expat-help
expat-devel
expat-debugsource
expat-debuginfo
expat
mingw-expat
expat (Ubuntu package)
expat (Debian package)

Install updates from vendor's website.

expat - update to 2.8.3
xmlrpc-c - addressed in versions 1.51.06-4, 1.51.08-5, 1.59.02-4
xmlrpc-c-debuginfo - addressed in versions 1.51.06-4, 1.51.08-5, 1.59.02-4
xmlrpc-c-debugsource - addressed in versions 1.51.06-4, 1.51.08-5, 1.59.02-4
xmlrpc-c-help - addressed in versions 1.51.06-4, 1.51.08-5, 1.59.02-4
xmlrpc-c-devel - addressed in versions 1.51.06-4, 1.51.08-5, 1.59.02-4
expat-help - update to 2.8.1-5
expat-devel - update to 2.8.1-5
expat-debugsource - update to 2.8.1-5
expat-debuginfo - update to 2.8.1-5
expat - update to 2.8.1-5
mingw-expat - addressed in versions 2.8.3-1.fc43, 2.8.3-1.fc44, 2.8.3-1.fc45
expat (Ubuntu package) - addressed in versions 2.1.0-4ubuntu1.4+esm13, 2.1.0-7ubuntu0.16.04.5+esm14, 2.2.5-3ubuntu0.9+esm5, 2.2.9-1ubuntu0.8+esm3, 2.4.7-1ubuntu0.9, 2.6.1-2ubuntu0.6, 2.7.4-1ubuntu0.2
expat (Debian package) - update to 2.8.3-1~deb13u1

• https://bugzilla.mozilla.org/show_bug.cgi?id=2053153
• https://github.com/libexpat/libexpat/pull/1296
• http://www.openwall.com/lists/oss-security/2026/08/11/5

• Out-of-bounds read in libexpat
• Debian update for expat
• Fedora 44 update for mingw-expat
• Fedora 43 update for mingw-expat
• Fedora 45 update for mingw-expat
• openEuler update for expat
• openEuler 24.03 LTS SP1 update for xmlrpc-c
• openEuler 22.03 LTS SP4 update for xmlrpc-c
• openEuler 20.03 LTS SP4 update for xmlrpc-c
• openEuler 24.03 LTS SP3 update for xmlrpc-c
• openEuler 24.03 LTS SP4 update for xmlrpc-c
• Ubuntu update for expat