CVE-2026-107738: Sumatrapdfreader Sumatrapdf

Medium severity, CVSS 6.8. EPSS: 0.1% chance of exploitation in the next 30 days.

SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, ChmFile::GetCharZ() narrows file-controlled unsigned string offsets from /#WINDOWS and /#IVB to signed integers without a lower-bound check. An offset that becomes negative can make the function read before the /#STRINGS buffer, causing deterministic application termination. No broader impact is claimed beyond the advisory-supported conditions. No fixed version is available as of this review.

Affected products

• Sumatrapdfreader Sumatrapdf: up to and including 3.6.1

Published 2026-10-08. Last modified 2026-10-08.