Buffer Overflow Issue in SumatraPDF Reader by SumatraPDF
CVE-2026-107738

6.8MEDIUM

Key Information:

Vendor

SumatraPDFreader

Status
SumatraPDF
Vendor
CVE Published:
8 October 2026

What is CVE-2026-107738?

The SumatraPDF reader, a versatile application for Windows, contains a vulnerability in its ChmFile::GetCharZ() function. In versions 3.6.1 and earlier, the function fails to validate certain file-controlled unsigned string offsets, resulting in negative values being interpreted as signed integers. This oversight allows the function to read beyond the designated /#STRINGS buffer, which can lead to unexpected application crashes. No remediation has been provided, and users are advised to remain cautious when using affected versions.

Affected Version(s)

sumatrapdf <= 3.6.1

References

https://github.com/sumatrapdfreader/sumatrapdf/security/a...
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https://github.com/sumatrapdfreader/sumatrapdf/commit/622...
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CVSS V4

Score:
6.8
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.