CVE-2026-25961 SumatraPDF Update MITM -> Arbitrary Code Execution
A network attacker can intercept update requests to inject malicious installers, leading to arbitrary code execution on Windows systems.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-25961?
CVE-2026-25961 is a high-severity vulnerability in sumatrapdfreader sumatrapdf, published on 9 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official 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.
Which versions are affected by CVE-2026-25961?
It affects 1 product.
Products include Sumatrapdfreader Sumatrapdf.
How do I fix CVE-2026-25961?
No fix has been published for CVE-2026-25961 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-25961 being exploited?
There is no known exploitation of CVE-2026-25961 in the wild and no public exploit code.
Public exploit code: 1 Exploit-DB entry and 1 proofs of concept on GitHub.
Other vulnerabilities in sumatrapdfreader sumatrapdf
Sources
Also known as GHSA-xpm2-rr5m-x96q.