What is CVE-2026-25961?

CVE-2026-25961 is a high-severity vulnerability in Sumatrapdfreader Sumatrapdf, classified under Improper Certificate Validation. CVSS score: 7.5/10. Published 2026-02-09.

How severe is CVE-2026-25961?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Sumatrapdfreader Sumatrapdf

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 at…

Vulnerability class: Improper Certificate Validation

EPSS: 0.004 (35.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H.

Affected products

Sumatrapdfreader Sumatrapdf — versions >= 3.5.0, <= 3.5.2

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)

Frequently asked questions

What is CVE-2026-25961?: CVE-2026-25961 is a high-severity vulnerability in Sumatrapdfreader Sumatrapdf, classified under Improper Certificate Validation. CVSS score: 7.5/10. Published 2026-02-09.
How severe is CVE-2026-25961?: High severity. CVSS v3 base score is 7.5 out of 10.