Improper Certificate Validation Affecting sumatrapdf package, versions [3.5,3.6)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-UNMANAGED-SUMATRAPDF-15253614
- published10 Feb 2026
- disclosed9 Feb 2026
- creditHaein Lee
Introduced: 9 Feb 2026
CVE-2026-25961 (opens in a new tab)How to fix?
Upgrade sumatrapdf to version 3.6 or higher.
Overview
Affected versions of this package are vulnerable to Improper Certificate Validation due to the disabled TLS hostname verification process disabling TLS hostname verification (INTERNET_FLAG_IGNORE_CERT_CN_INVALID flag). An attacker can execute arbitrary code by intercepting the update request and injecting a malicious installer URL.