CVE-2026-25961
Undergoing Analysis Undergoing Analysis - In Progress
Insecure Update Mechanism in SumatraPDF Allows Remote Code Execution

Publication date: 2026-02-09

Last updated on: 2026-02-20

Assigner: GitHub, Inc.

Description
SumatraPDF is a multi-format reader for Windows. In 3.5.0 through 3.5.2, SumatraPDF's update mechanism disables TLS hostname verification (INTERNET_FLAG_IGNORE_CERT_CN_INVALID) and executes installers without signature checks. A network attacker with any valid TLS certificate (e.g., Let's Encrypt) can intercept the update check request, inject a malicious installer URL, and achieve arbitrary code execution.
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Meta Information
Published
2026-02-09
Last Modified
2026-02-20
Generated
2026-06-16
AI Q&A
2026-02-10
EPSS Evaluated
2026-06-15
NVD
CVE-2026-25961
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
sumatrapdfreader sumatrapdf From 3.5 (inc) to 3.5.2 (inc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-295 The product does not validate, or incorrectly validates, a certificate.
CWE-494 The product downloads source code or an executable from a remote location and executes the code without sufficiently verifying the origin and integrity of the code.
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Executive Summary

This vulnerability affects SumatraPDF versions 3.5.0 through 3.5.2. The update mechanism in these versions disables TLS hostname verification and executes installers without verifying their digital signatures. As a result, a network attacker who has any valid TLS certificate, such as one from Let's Encrypt, can intercept the update check request, inject a malicious installer URL, and cause the application to execute arbitrary code.

Impact Analysis

This vulnerability can lead to arbitrary code execution on your system if exploited. An attacker can intercept the update process, deliver a malicious installer, and run harmful code with the privileges of the user running SumatraPDF. This can result in system compromise, data theft, or further malware installation.

Compliance Impact

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