Vulnerability Details CVE-2026-25961
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 2.7%
CVSS Severity
CVSS v3 Score 7.5
Products affected by CVE-2026-25961
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cpe:2.3:a:sumatrapdfreader:sumatrapdf:*