CVE-2026-94127
F5 BIG-IP APM
Summary
F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability
F5 BIG-IP APM contains a heap-based buffer overflow vulnerability when access policy and an OAuth profile are configured on a virtual server. This vulnerability could allow an unauthenticated attacker to perform remote code execution.
Published 2026-09-22 · first seen here 2026-10-10
CISA required action (due 2026-09-25): Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Analysis & write-ups
Exploit availability
Public exploit code lowers the bar for attackers, so prioritise patching and hunting. These repositories are unverified. Fake PoCs that contain malware are common, so never run them outside an isolated lab.
- watchtowrlabs/watchTowr-vs-f5-bigip-PreAuth-RCE-CVE-2026-94127 · ★15 · created 2026-09-24
- FurkanKAYAPINAR/CVE-2026-94127 · ★0 · created 2026-09-23
Where it shows in your logs
CISA requires forensic triage for this CVE (BOD 26-04): check affected systems for signs of compromise, don't just patch.
Edge or network appliance (firewall, VPN, gateway) · Memory corruption (overflow, use-after-free) high confidence
Appliances usually run no EDR, so device logs, firewall flow logs and the vendor's integrity checker are often the only evidence. Get the logs off the box: attackers often wipe local logs.
What to look for
- Appliance crashes, core dumps or unexpected reboots, often from repeated attempts
- Session or config changes right after a crash
- Configuration changes, new local admin accounts or new VPN users on the appliance
- Admin or VPN logins from unfamiliar IPs, especially VPS or hosting providers
- New outbound connections from the appliance's own IP (it should rarely start connections)
- Gaps in the appliance's logs, unexpected reboots or crashes, or logs that were cleared
Data sources
Appliance system and admin logs · ATT&CK DS0015 Application Log Content
- Sentinel
CommonSecurityLog (CEF from Fortinet, Palo Alto, Check Point, Cisco)Syslog- Splunk
Vendor add-ons: fortigate_event, pan:system, pan:config, cisco:asa, citrix:netscaler:syslog, f5:bigip:syslogChange.All_Changes- CrowdStrike
Falcon Next-Gen SIEM: third-party firewall / VPN connectors
Authentication and sessions · ATT&CK DS0028 Logon Session Creation / DS0002 User Account Authentication
- Sentinel
SigninLogsSecurityEvent (4624, 4625, 4648)DeviceLogonEventsIdentityLogonEvents_Im_Authentication- Splunk
Authentication.Authenticationpan:globalprotectVPN sourcetypes- CrowdStrike
UserLogonUserLogonFailed2Falcon Identity Protection 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
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
A generic baseline worked out from the product type and weakness (CWE-122), not a detection. Check table and field names against your environment. Hunt queries for Sigma, Splunk, Sentinel and CrowdStrike are coming.
News & advisories
- 28th September – Threat Intelligence Report · Check Point Research