CVE-2026-91812
foxit pdf editor
Summary
A vulnerability in Foxit PDF Editor/Reader’s update mechanism allows man-in-the-middle attackers to bypass certificate validation and package integrity checks, potentially enabling arbitrary code execution with system privileges.
Published 2026-09-23 · first seen here 2026-10-10
Analysis & write-ups
No technical write-up from a research team yet. Contact Zero checks Unit 42, Google/Mandiant, Microsoft, Talos, CrowdStrike, Rapid7, watchTowr and others several times a day, plus NVD and CISA reference links.
Where it shows in your logs
Client software (browser, Office, PDF, archive tools) · Command or code injection (remote code execution) medium confidence
What to look for
- Shell metacharacters or encoded payloads in request parameters (; | ` $( %0a)
- The vulnerable process spawning shells, then downloaders (curl, wget, certutil, Invoke-WebRequest)
- The vulnerable app starting script or command interpreters (e.g. winword.exe or chrome.exe spawning powershell.exe, cmd.exe, mshta.exe, wscript.exe)
- Files written to Startup folders, %AppData% or %Temp% right after opening a document or page
- Outbound connections from processes the vulnerable app spawned
- Related email delivery: attachments of the exploited file type, or links from the same campaign
Data sources
Process creation · ATT&CK DS0009 Process Creation
- Sentinel
DeviceProcessEventsSecurityEvent (4688)Sysmon Event ID 1_Im_ProcessCreate- Splunk
Endpoint.ProcessesXmlWinEventLog:Microsoft-Windows-Sysmon/OperationalWinEventLog:Security (4688)- CrowdStrike
ProcessRollup2SyntheticProcessRollup2
File creation · ATT&CK DS0022 File Creation
- Sentinel
DeviceFileEventsSysmon Event ID 11_Im_FileEvent- Splunk
Endpoint.FilesystemSysmon Event ID 11- CrowdStrike
NewExecutableWrittenNewScriptWritten*FileWritten events
Network connections · ATT&CK DS0029 Network Connection Creation / Network Traffic Flow
- Sentinel
DeviceNetworkEventsCommonSecurityLog (firewall)_Im_NetworkSession- Splunk
Network_Traffic.All_TrafficFirewall sourcetypes (pan:traffic, fortigate_traffic, cisco:asa)- CrowdStrike
NetworkConnectIP4NetworkReceiveAcceptIP4NetworkConnectIP6
Email delivery · ATT&CK DS0015 Application Log Content
- Sentinel
EmailEventsEmailAttachmentInfoEmailUrlInfo- Splunk
Email.All_Email- CrowdStrike
Falcon Next-Gen SIEM: email security connectors
A generic baseline worked out from the product type and weakness (CWE-295), not a detection. Check table and field names against your environment. Hunt queries for Sigma, Splunk, Sentinel and CrowdStrike are coming.