Affects widely deployed NGINX JavaScript (njs); worker crashes cause service disruption/DoS across internet-facing deployments.
CVE-2026-78222
NGINX JavaScript ngx.fetch() flaw lets crafted HTTP responses crash workers (DoS)
Is CVE-2026-78222 being exploited?
Not confirmed. CVE-2026-78222 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.37% probability of exploitation in the next 30 days.
How severe is CVE-2026-78222?
CVE-2026-78222 is rated High. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-78222?
Not known from our data. No patch reference has been recorded for CVE-2026-78222, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2026-78222 affect?
CVE-2026-78222 affects NGINX with JavaScript (njs) / ngx.fetch(), NGINX data-plane deployments using njs. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-78222?
Avoid fetching untrusted responses; apply vendor patch when released; restrict upstream control.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote denial-of-service: a crafted HTTP response read by ngx.fetch() triggers a worker crash via Response.statusText.
Patch when possible
- affected>= 0.5.1 and < 1.0.1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.