CVE-2026-78222 NGINX ngx_http_js_module vulnerability
Remote attackers can crash NGINX workers by sending malformed HTTP responses to trusted JavaScript code using ngx.fetch().
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-78222?
CVE-2026-78222 is a high-severity vulnerability in F5 NGINX JavaScript, published on 2 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability exists in NGINX JavaScript where a malformed HTTP response received by ngx.fetch() can crash an NGINX worker when trusted JavaScript reads Response.statusText. Exploitation requires control or influence over the fetched HTTP response.
Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Weakness: CWE-476
Which versions are affected by CVE-2026-78222?
How do I fix CVE-2026-78222?
Apply the vendor's patch.
Is CVE-2026-78222 being exploited?
There is no known exploitation of CVE-2026-78222 in the wild and no public exploit code.
Sources
Also known as AZL-99300, DEBIAN-CVE-2026-78222, GHSA-27f9-cgjj-wvcv, UBUNTU-CVE-2026-78222.