---
id: CVE-2026-107738
title: SumatraPDF is a multi-format reader for Windows
summary: >-
  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 ne…
severity: none
cwe:
  - CWE-125
published: '2026-10-08'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T23:17:00.230'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-107738'
references:
  - url: >-
      https://github.com/sumatrapdfreader/sumatrapdf/commit/62254ed6d781ceb5cd16489bb423e7f591cd72c4
    label: security-advisories@github.com
  - url: >-
      https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-33jg-vxm6-8mxx
    label: security-advisories@github.com
tags:
  - nvd
ingestedAt: '2026-10-09T00:19:50.973Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.