How severe is CVE-2026-25961?

CVE-2026-25961 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-25961 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25961?

CVE-2026-25961 affects Sumatrapdfreader Sumatrapdf. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25961?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-25961 have an EU (EUVD) identifier?

Yes. CVE-2026-25961 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6869.

When was CVE-2026-25961 published?

CVE-2026-25961 was published on 2026-02-09 and last updated on 2026-06-17.

CVE-2026-25961

CVE-2026-25961 is a high-severity vulnerability in Sumatrapdfreader Sumatrapdf with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-494.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (36th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-6869
Weakness: CWE-494
Affected product: Sumatrapdfreader Sumatrapdf
Published: 2026-02-09
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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 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.
How severe is CVE-2026-25961?: CVE-2026-25961 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-25961 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25961?: CVE-2026-25961 affects Sumatrapdfreader Sumatrapdf. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25961?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-25961 have an EU (EUVD) identifier?: Yes. CVE-2026-25961 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6869.
When was CVE-2026-25961 published?: CVE-2026-25961 was published on 2026-02-09 and last updated on 2026-06-17.

References

https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-xpm2-rr5m-x96q

Affected products (1)

cpe:2.3:a:sumatrapdfreader:sumatrapdf:*:*:*:*:*:*:*:*

More vulnerabilities in Sumatrapdfreader Sumatrapdf

CVE-2012-4896 — Critical (CVSS 9.3): Heap-based buffer overflow in SumatraPDF before 2.1 allows remote attackers to execute arbitrary code via a crafted PDF…
CVE-2012-4895 — Critical (CVSS 9.3): Heap-based buffer overflow in SumatraPDF before 2.1 allows remote attackers to execute arbitrary code via a crafted PDF…
CVE-2009-4117 — Critical (CVSS 9.3): Multiple stack-based buffer overflows in pdf_shade4.c in MuPDF before commit 20091125231942, as used in SumatraPDF…
CVE-2026-23512 — High (CVSS 8.6): SumatraPDF is a multi-format reader for Windows. In 3.5.2 and earlier, there is a Untrusted Search Path vulnerability…
CVE-2026-25880 — High (CVSS 7.8): SumatraPDF is a multi-format reader for Windows. In 3.5.2 and earlier, the PDF reader allows execution of a malicious…
CVE-2012-5340 — High (CVSS 7.8): SumatraPDF 2.1.1/MuPDF 1.0 allows remote attackers to cause an Integer Overflow in the lex_number() function via a…

All CVEs affecting Sumatrapdfreader Sumatrapdf →

Other CWE-494 vulnerabilities

CVE-2020-1595 — Critical (CVSS 9.9): <p>A remote code execution vulnerability exists in Microsoft SharePoint where APIs aren't properly protected from…
CVE-2020-1210 — Critical (CVSS 9.9): <p>A remote code execution vulnerability exists in Microsoft SharePoint when the software fails to check the source…
CVE-2026-42248 — Critical (CVSS 9.8): Ollama for Windows does not perform integrity or authenticity verification of downloaded update executables. Unlike…
CVE-2026-34841 — Critical (CVSS 9.8): Bruno is an open source IDE for exploring and testing APIs. Prior to 3.2.1, Bruno was affected by a supply chain attack…
CVE-2026-3000 — Critical (CVSS 9.8): IDExpert Windows Logon Agent developed by Changing has a Remote Code Execution vulnerability, allowing unauthenticated…
CVE-2026-2999 — Critical (CVSS 9.8): IDExpert Windows Logon Agent developed by Changing has a Remote Code Execution vulnerability, allowing unauthenticated…

Browse all CWE-494 vulnerabilities →