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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Fixes

Solution

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Workaround

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History

Mon, 09 Feb 2026 21:45:00 +0000

Type Values Removed Values Added
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.
Title SumatraPDF Update MITM -> Arbitrary Code Execution
Weaknesses CWE-295
CWE-494
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-09T21:34:05.203Z

Reserved: 2026-02-09T17:13:54.066Z

Link: CVE-2026-25961

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-02-09T22:16:04.750

Modified: 2026-02-09T22:16:04.750

Link: CVE-2026-25961

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses