Arbitrary Code Execution Vulnerability in SumatraPDF by SumatraPDF Reader
CVE-2026-25961

7.5HIGH

Key Information:

Vendor

SumatraPDFreader

Status
SumatraPDF
Vendor
CVE Published:
9 February 2026

What is CVE-2026-25961?

SumatraPDF, a versatile multi-format reader for Windows, has a critical flaw in versions 3.5.0 to 3.5.2. The application's update mechanism disables TLS hostname verification and allows for the execution of unsigned installers. This vulnerability permits a network attacker possessing a valid TLS certificate to intercept update requests, thereby injecting a malicious installer URL and executing arbitrary code. Users of affected versions should prioritize applying patches or updates to secure their systems from potential exploitation.

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Deploy the Patch

Affected Version(s)

sumatrapdf >= 3.5.0, <= 3.5.2

References

https://github.com/sumatrapdfreader/sumatrapdf/security/a...
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CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Privileges Required:
None
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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