Unprotected Alternate Channel in BIG-IP - CVE-2026-40435
Published: May 14, 2026
Vulnerability identifier: #VU131405
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-40435
CWE-ID: CWE-420
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: F5 Networks
Affected software:
BIG-IP
BIG-IP
Detailed vulnerability description
The vulnerability allows a remote attacker to connect to the BIG-IP control plane HTTP services from blocked addresses.
The vulnerability exists due to unprotected alternate channel in httpd access control when handling requests to endpoints not covered by configured IP-based access restrictions. A remote attacker can send requests to exposed endpoints to connect to the BIG-IP control plane HTTP services from blocked addresses.
Valid login credentials are still required to interact with the BIG-IP system, and there is no data plane exposure.
How to mitigate CVE-2026-40435
Install security update from vendor's website.