CVE-2026-25961 PoC — SumatraPDF Update MITM -> Arbitrary Code Execution

Source

https://github.com/mbanyamer/CVE-2026-25961-SumatraPDF-3.5.0---3.5.2-RCE

Associated Vulnerability

Title: SumatraPDF Update MITM -> Arbitrary Code Execution (CVE-2026-25961)
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.

Description

SumatraPDF versions 3.5.0 to 3.5.2 disable TLS hostname verification during update checks #   (using INTERNET_FLAG_IGNORE_CERT_CN_INVALID) and do not perform any signature or integrity #   validation on the downloaded installer.

File Snapshot

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