CVE-2026-25961
SumatraPDF Update MITM -> Arbitrary Code Execution
No known exploitation. EPSS puts it in the 38th percentile. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
- Sumatrapdfreader SumatrapdfAffected: ≥ 3.5, ≤ 3.5.2Upgrade to: after 3.5.2Stated by: NVD
- Krzysztof Kowalczyk SumatraPDFAffected: 3.5.0Upgrade to: not statedStated by: BDU
Versions as the sources state them. Full version matrix after sign-in
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.4% chance of exploitation activity in the next 30 days, which ranks it in the 38th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
5 events over 11 days, from the signal feeds we watch.
- Patch availablerecord updated
- Publishedweakness classified, att&ck mapped
Affected products
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Scored 7.5 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction RequiredA user must click a link, open a file, or perform some action
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality HighTotal information disclosure — all data in the component is compromised
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability HighTotal denial of service — the component is completely unavailable
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
- CollectionT1557Adversary-in-the-Middlehigh confidence
- Initial AccessT1195Supply Chain Compromisehigh confidence
Sources
References in the record
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