Widely used web server; potential RCE via HTTP/3 QUIC affects many deployments.
CVE-2026-42530
RCE via HTTP/3 QUIC in NGINX Open Source QUIC module.
Is CVE-2026-42530 being exploited?
Not confirmed. CVE-2026-42530 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 3.8% probability of exploitation in the next 30 days.
How severe is CVE-2026-42530?
CVE-2026-42530 is rated Critical with a CVSS score of 9.2. 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-2026-42530?
Yes. A fix has been recorded for CVE-2026-42530. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-42530 affect?
CVE-2026-42530 affects NGINX Open Source, ngx_http_v3_module, HTTP/3 QUIC module. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-42530?
Patch when available; review exposure and disable HTTP/3 if not needed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via crafted HTTP/3 session; use-after-free may allow code execution when ASLR is bypassed/disabled.
Immediate action required
- affected>= 1.31.0 and < 1.31.2
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.