Check Point Advisories

F5 NGINX JavaScript Heap Overflow (CVE-2026-8711)

Vulnerability
Protection

Check Point Reference:	CPAI-2026-9717
Date Published:	3 Aug 2026
Severity:	Critical
Last Updated:	Monday 03 August, 2026
Source:
Industry Reference:	CVE-2026-8711
Protection Provided by:	Security Gateway R81, R80, R77, R75
Who is Vulnerable?	F5 NGINX JavaScript 0.9.4 and later, prior to 0.9.9
Vulnerability Description	A heap overflow vulnerability in F5 NGINX JavaScript allows unauthenticated attackers to execute code or cause a denial of service by sending crafted HTTP requests when the js_fetch_proxy directive is configured with client-controlled variables.

Protection Overview

This protection detects attempts to exploit this vulnerability.

In order for the protection to be activated, update your Security Gateway product to the latest IPS update. For information on how to update IPS, go to SBP-2006-05, click on Protection tab and select the version of your choice.

Security Gateway R81 / R80 / R77 / R75

In the IPS tab, click Protections and find the F5 NGINX JavaScript Heap Overflow (CVE-2026-8711) protection using the Search tool and Edit the protection's settings.
Install policy on all Security Gateways.

This protection's log will contain the following information:

Attack Name: Web Server Enforcement Violation.
Attack Information: F5 NGINX JavaScript Heap Overflow (CVE-2026-8711)