Integer overflow in Libxml2 - CVE-2026-86143
Published: September 8, 2026
Vulnerability identifier: #VU147361
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-2026-86143
CWE-ID: CWE-190
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause negative lengths to reach write callbacks.
The vulnerability exists due to an integer overflow in xmlOutputWriteCallback and xmlBufUse in xmlIO when invoking write callbacks. A remote attacker can invoke an output write callback to cause negative lengths to reach write callbacks.
The issue is caused by an inconsistency between xmlOutputWriteCallback and xmlBufUse.
Affected software
Libxml2
How to mitigate CVE-2026-86143
Install security update from vendor's website.
Libxml2 - update to 2.15.4