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
None
Shenlong Bot has cached this for you
Remarks
1. It is advised to access via the original source first.2. Local POC snapshots are reserved for subscribers — if the original source is unavailable, the local mirror is part of the paid plan.3. Mirroring, verifying, and maintaining this POC archive takes ongoing effort, so local snapshots are a paid feature. Your subscription keeps the archive online — thank you for the support. View subscription plans →