CVE-2026-86138: Xmlsoft LIBXML2

High severity, CVSS 7.8. EPSS: 0.1% chance of exploitation in the next 30 days.

In libxml2 before 2.15.4, xmlDictAddQString in dict.c has an integer overflow and resultant heap-based buffer overflow.

Affected products

• Xmlsoft LIBXML2: before 2.15.4 (fixed in 2.15.4)

Published 2026-09-05. Last modified 2026-09-15.