All vulnerabilities
CVE-2026-107737GHSA-8p34-f32f-7rmq

SumatraPDF CHM `its://` signed index causes an out-of-bounds object lookup

sumatrapdfreader sumatrapdf
Open in ThreatlineRecord JSON
CVSS
5.7Medium
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 13 Oct 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.12%Chance of exploitation activity in the next 30 days, higher than 1% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published8 Oct 2026Updated 13 Oct 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

Description

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.

Text from CVE List

Affected versions 2

  • sumatrapdfaffected: <= 3.6.1CVE List
  • SumatraPDF3.6.1GitHub

References 2