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Vulnerabilities

Vulnerability · CVE-2026-25961

SumatraPDF is a multi-format reader for Windows.

Published Feb 9, 2026 · catalog updated Feb 10, 2026 · SumatraPDF is a multi-format

Last checked Nov 5, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-25961. EPSS is 0.45%. Act only if a listed version of SumatraPDF is a multi-format is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (SumatraPDF is a multi-format).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.45%
Remediation
Advisory link
Affected products
vendor sumatrapdfreader sumatrapdf 3.5.0, ≤ 3.5.2

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor sumatrapdfreader sumatrapdf 3.5.0, ≤ 3.5.23.5.0, ≤ 3.5.2

How to fix CVE-2026-25961

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-25961. EPSS is 0.45%. Act only if a listed version of SumatraPDF is a multi-format is installed.

Which versions are affected?

Compare what you have installed with sumatrapdfreader sumatrapdf 3.5.0, ≤ 3.5.2 3.5.0, ≤ 3.5.2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.45%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Windows security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 9, 2026 · EUVD

    Detected

    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

  2. Feb 10, 2026 · EUVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-25961

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-25961

    30-day exploitation probability 0.45%

    first.org
  • EUVDVulnerability recordEUVD-2026-6869

    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.

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Nov 5, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 5, 2026
  • CVE.orgNov 4, 2026
  • EUVDNov 3, 2026