---
id: CVE-2026-107737
title: SumatraPDF is a multi-format reader for Windows
summary: >-
  SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, and in
  pre-release 3.7.0.20369 when WebView2 is absent or cannot initialize,
  ParseProtoUrl() accepts the signed host component of an its:// URL and
  FindHtmlWindowById…
severity: medium
cwe:
  - CWE-129
published: '2026-10-08'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T17:17:17.340'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-107737'
references:
  - url: >-
      https://github.com/sumatrapdfreader/sumatrapdf/commit/596c7e26e983549a77a3a38cae1147ab73792929
    label: security-advisories@github.com
  - url: >-
      https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-8p34-f32f-7rmq
    label: security-advisories@github.com
  - url: >-
      https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-8p34-f32f-7rmq
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
tags:
  - nvd
  - cve.org
  - exploit-available
epss: 0.00182
epssPercentile: 0.07701
ingestedAt: '2026-10-09T00:19:50.972Z'
vendor: sumatrapdfreader
product: sumatrapdf
affected:
  - sumatrapdf <= 3.6.1
cvss: 5.7
cvssVector: 'CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-13T16:27:49.009801Z'
cvssSource: cna
---

## Overview

SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, and in pre-release 3.7.0.20369 when WebView2 is absent or cannot initialize, ParseProtoUrl() accepts the signed host component of an its:// URL and FindHtmlWindowById() uses it directly as an index into gHtmlWindows. Opening a crafted CHM through the IE fallback backend with a negative or otherwise out-of-range window identifier can cause an out-of-bounds pointer read followed by an invalid object callback dereference and process termination. No fixed version is available as of this review.

## Remediation

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