CVE-2026-91803
foxit pdf editor
Summary
A local privilege escalation vulnerability exists in the updater of Foxit PDF Editor/Reader due to unsafe loading of dynamic-link libraries from a user-writable directory during high-privilege operations. A local attacker could exploit this issue to execute code with elevated 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) · Local privilege escalation medium confidence
What to look for
- SYSTEM or root processes started from a non-admin user's session
- Known exploit tool names or unsigned binaries run from user-writable folders (Temp, Downloads, /tmp)
- 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
Account and group changes · ATT&CK DS0002 User Account Creation / Modification
- Sentinel
SecurityEvent (4720, 4728, 4732, 4756)AuditLogsIdentityDirectoryEvents- Splunk
Change.All_Changes (Account_Management)WinEventLog:Security (4720, 4732)- CrowdStrike
UserAccountCreatedUserAccountAddedToGroup
A generic baseline worked out from the product type and weakness (CWE-427), not a detection. Check table and field names against your environment. Hunt queries for Sigma, Splunk, Sentinel and CrowdStrike are coming.