CVE
CVE-2026-25961
SumatraPDF Update MITM -> Arbitrary Code Execution
SumatraPDF is a multi-format reader for Windows. In 3.5.0 through 3.5.2, SumatraPDF's update mechanism disables TLS hostname verification (INTERNETFLAGIGNORECERTCN_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.
Package Versions Affected
Package Version
patch Availability
No items found.
Automatically patch vulnerabilities without upgrading
Fix Without Upgrading
Detect compatible fix
Apply safe remediation
Fix with a single pull request
CVSS Version
Severity
Base Score
CVSS Version
Score Vector
C
H
U
7.5
-
3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
C
H
U
-
Related Resources
No items found.
References
https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/25xxx/CVE-2026-25961.json, https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-xpm2-rr5m-x96q, https://nvd.nist.gov/vuln/detail/CVE-2026-25961
Basic Information
Ecosystem
