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TI-2026-20986 Aliases CVE-2026-25961

SumatraPDF Update MITM -> Arbitrary Code Execution

Priority LOW 35CWE-295Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
High
Impact type
Spoofing, Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-295 and CWE-494.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00449 39th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
sumatrapdfreadersumatrapdf3.5.0 – 3.5.2—No fix listedCNA
  • sumatrapdf Vendorsumatrapdfreader Affected 3.5.0 – 3.5.2 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:sumatrapdfreader:sumatrapdf:*:*:*:*:*:*:*:*3.5 – 3.5.2Vulnerablesumatrapdfreader
  • cpe:2.3:a:sumatrapdfreader:sumatrapdf:*:*:*:*:*:*:*:* Versions 3.5 – 3.5.2 Vulnerable ·sumatrapdfreader

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-25961

References

Exploit 1

  • TI-2026-18936 SumatraPDF has an Untrusted Search Path in sumatrapdf/src/AppTools.cpp CVSS 3.1HIGH 8.6
  • TI-2025-35489 A null pointer dereference vulnerability was discovered in SumatraPDF 3.5.2 during the… CVSS 3.1HIGH 7.3
  • TI-2012-04514 SumatraPDF 2.1.1/MuPDF 1.0 allows remote attackers to cause an Integer Overflow in the… CVSS 3.1HIGH 7.8
  • TI-2026-19293 SumatraPDF's Integer Underflow in PalmDbReader Leads to Crash CVSS 3.1MEDIUM 5.5
  • TI-2023-16705 A buffer overflow in SumatraPDF Reader v3.4.6 allows attackers to cause a Denial of… CVSS 3.1MEDIUM 5.5
  • TI-2009-01521 Heap-based buffer overflow in the loadexponentialfunc function in mupdf/pdf_function.c in… CVSS 3.1MEDIUM 5.4
See all 12 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences