CVE-2026-8711 NGINX JavaScript vulnerability

Critical 9.2 Published 19 May 2026 Updated 21 May 2026

An unauthenticated attacker can trigger a heap buffer overflow in NGINX JavaScript, potentially causing a service restart or remote code execution.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-8711?

CVE-2026-8711 is a critical memory corruption vulnerability in F5 NGINX JavaScript, published on 19 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

NGINX JavaScript has a vulnerability when the js_fetch_proxy directive is configured with at least one client-controlled NGINX variable (for example, $http_*, $arg_*, $cookie_*) and a location invoking the ngx.fetch() operation from NGINX JavaScript. An unauthenticated attacker can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Weakness: CWE-122

Which versions are affected by CVE-2026-8711?

It affects 1 product.

Products include F5 Njs.

How do I fix CVE-2026-8711?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-8711 being exploited?

There is no known exploitation of CVE-2026-8711 in the wild and no public exploit code.

Sources

Also known as ALPINE-CVE-2026-8711, AZL-87117, BELL-CVE-2026-8711, DEBIAN-CVE-2026-8711, GHSA-pj32-6rxc-gcmq, UBUNTU-CVE-2026-8711 and 1 more.