CVE-2026-107737
SumatraPDF CHM `its://` signed index causes an out-of-bounds object lookup
- State
- Published
- Severity
- 5.7 Medium
- Published
- Oct 8, 2026
- Updated
- Oct 13, 2026
- Reserved
- Oct 8, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 5.7 Medium | 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 | GitHub_M |
Weaknesses
- CWE-129 Improper Validation of Array Index
Affected Products
| Product | Versions |
|---|---|
sumatrapdfsumatrapdfreader |
|
References
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