CVE-2026-94127: Critical Unauthenticated RCE in F5 BIG-IP APM

Overview

On September 22, 2026, F5 published a security advisory for CVE-2026-94127, a critical heap-based buffer overflow vulnerability affecting F5 BIG-IP Access Policy Manager (APM). The vulnerability has a CVSS v3.1 score of 9.8. An unauthenticated attacker with network access to an affected virtual server may be able to achieve remote code execution (RCE) by sending specifically crafted traffic.

BIG-IP APM provides identity-aware access control for applications and other corporate resources and can integrate with authentication technologies including OAuth, OpenID Connect, and SAML. CVE-2026-94127 is not exposed in a default configuration: exploitation requires a BIG-IP virtual server with both an APM access policy and an OAuth profile configured. Because affected BIG-IP systems may process traffic at an organization's network edge, organizations using this configuration should prioritize remediation.

The vulnerability affects the data plane and does not expose the BIG-IP control plane. BIG-IP systems operating in Appliance mode are also affected.

F5 lists the following affected release trains and corresponding fixed hotfixes:

• BIG-IP 21.1.0: versions prior to Hotfix-BIGIP-21.1.0.2.0.30.22-ENG

• BIG-IP 17.5.0: versions prior to Hotfix-BIGIP-17.5.1.9.0.160.12-ENG

• BIG-IP 17.1.0: versions prior to Hotfix-BIGIP-17.1.3.5.0.41.14-ENG

As of September 22, 2026, CVE-2026-94127 has been added to the CISA KEV while a publicly available proof of concept was not confirmed.

Mitigation guidance

Organizations running affected F5 BIG-IP deployments should apply the appropriate F5 hotfix as soon as operationally feasible, particularly where a vulnerable APM and OAuth configuration is reachable from untrusted networks.

F5 lists the following remediation versions:

• BIG-IP 21.1.0: update to Hotfix-BIGIP-21.1.0.2.0.30.22-ENG or later.

• BIG-IP 17.5.0: update to Hotfix-BIGIP-17.5.1.9.0.160.12-ENG or later.

• BIG-IP 17.1.0: update to Hotfix-BIGIP-17.1.3.5.0.41.14-ENG or later.

Administrators should first determine whether a BIG-IP APM access policy and an OAuth profile are configured together on a virtual server, since this configuration is required for exposure.

For organizations that cannot immediately apply the applicable update, F5 provides an iRule workaround through F5 Support. Customers should open a support case with F5 to obtain the vendor-provided workaround and follow F5's implementation guidance.

Rapid7 customers

Exposure Command, Vulnerability Management, and Nexpose

Exposure Command, Vulnerability Management, Nexpose customers can assess exposure to CVE-2026-94127 using vulnerability checks expected to be available in today’s (September 23) content release.

Updates

• September 22, 2026: Initial publication.