CVE-2026-94127: F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability

F5 BIG-IP APM is a memory-safety issue whose practical impact depends on the reachable parser, process privileges, platform protections, and reliability of attacker-controlled input.

How to check your systems

Confirm the exact affected build and component exposure, update from the vendor channel, review crash and restart telemetry, and keep network containment in place until the fixed process is running.

Record the running product build and enabled component from the vendor-supported inventory interface. Compare it with each affected range above, then check the documented authentication and network prerequisites. Keep the output, asset identifier, observation time, and advisory revision with the change ticket.

How to fix

Permanent remediation

1. Identify exact product versions, owners, exposure paths, and business-critical dependencies.
2. Apply the latest vendor remediation or isolate the vulnerable path when immediate patching is not possible.
3. Review available telemetry for exploitation attempts before restarting, rebuilding, or rotating evidence away.
4. Validate the fixed version and control health, then record any exception with an owner and expiry date.

Official remediation direction: CISA due date: 2026-09-25. This deadline applies to covered US federal civilian agencies; other organizations should set a risk-based deadline. 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. Official action

If you cannot patch yet

An iRule is available upon request. Open a ticket with F5 support to request this. Published workaround

Give any temporary control an owner and expiry, verify it covers every affected instance, and retain a rollback path. Remove it only after the permanent remediation is verified.

Detection and post-fix validation

• Confirm the installed and running version of F5 BIG-IP APM against the current vendor advisory.
• Check whether the vulnerable interface is reachable from untrusted networks or lower-privileged identities.
• Look for new accounts, privilege changes, crashes, child processes, or unusual outbound traffic associated with the component.
• Run a post-remediation service and security-control health check and retain evidence with the change record.

A clean scan or a version match alone does not rule out earlier compromise. If telemetry suggests exploitation, preserve evidence and follow the incident-response process alongside patching.

Timeline and exploitation status

• September 22, 2026 — Source entry published.
• September 22, 2026 — Added to CISA KEV.
• September 22, 2026 — CVE record published.
• September 23, 2026 — Source record updated.

Record publication and KEV addition dates describe those source events; they do not establish when exploitation first began.

The linked official record reports exploitation in the wild. This does not establish that any particular deployment has been compromised.

Public proof-of-concept availability is not independently established here. Recheck the vendor and government records as evidence changes.

Primary sources and references

• CNA-linked reference: my.f5.com
• CISA-linked vendor guidance: www.cisa.gov
• CISA-linked vendor guidance: www.cisa.gov
• CISA-linked vendor guidance: nvd.nist.gov
• CVE CNA: f5: CVE-2026-94127 CNA record
• CISA Known Exploited Vulnerabilities: CVE-2026-94127: F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability