Known exploited vulnerability · CISA KEV

CVE-2026-94127: 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.

CVE-2026-94127

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2026-09-22: attackers are using it right now.

CISA KEV: Listed; Added 2026-09-22 · federal fix-by 2026-09-25
EPSS (30 days): 27%; Higher than 98% of CVEs · 2026-11-01
CVSS v4.0: 9.3 Critical; CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

What CISA says

F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability

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.

NVD description · published 2026-09-22

When a BIG-IP APM access policy and an OAuth profile are configured on a virtual server, specific malicious traffic can lead to remote code execution (RCE). This vulnerability is only present when BIG-IP APM is configured as an OAuth Authorization Server. Deployments using APM strictly as an OAuth Client / Resource Server (without OAuth authorization server profiles configured) are not affected by this vulnerability. Impact: This vulnerability allows an unauthenticated attacker to perform remote code execution. The BIG-IP system in Appliance mode is also vulnerable. This is a data plane issue; there is no control plane exposure. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

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How to check if you are exposed to CVE-2026-94127

Find every F5 BIG-IP APM system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
Compare each version with the fixed versions in the vendor advisory below. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2026-94127.

US federal agencies had to fix this by 2026-09-25. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Affected versions

Versions the National Vulnerability Database lists as vulnerable to CVE-2026-94127. Check the vendor advisory for the exact fixed builds before you sign anything off.

Product	Vulnerable versions
F5 Big-Ip Access Policy Manager	from 17.0.0 up to and including 17.1.3; from 17.5.0 up to and including 17.5.1; 21.1.0

Timeline

2026-09-22 · Published in the National Vulnerability Database
2026-09-22 · Added to CISA's Known Exploited Vulnerabilities catalog, the same day it was published
2026-09-25 · Fix-by date for US federal agencies, passed 37 days ago

Vendor advisories and fixes

https://my.f5.com/manage/s/article/K000162605

Weakness type

CWE-122

More exploited F5 vulnerabilities

CISA lists 8 exploited F5 vulnerabilities. The closest matches:

Keep going

Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.