Is there a public exploit for CVE-2026-42530?

Yes. Proof-of-concept code for CVE-2026-42530 has been published publicly.

Is there a proof of concept for CVE-2026-42530?

Yes — 3 proof-of-concept entries are linked on this page, from public repositories and community submissions. They are listed for authorised testing only.

How severe is CVE-2026-42530?

CVE-2026-42530 scores CVSS 9.2 (v4.0), rated critical. EPSS puts the chance of exploitation in the next 30 days at 6.22%.

What does CVE-2026-42530 affect?

CVE-2026-42530 affects F5 NGINX Open Source.

9.2 Critical

NGINX Open Source has a vulnerability in the ngxhttpv3module module.

CVE-2026-42530

NGINX Open Source has a vulnerability in the ngxhttpv3module module. When NGINX Open Source is configured to use the HTTP/3 QUIC module, a remote unauthenticated attacker along with conditions beyond their control can use a specially crafted HTTP/3 session to reopen a QPACK encoder stream. This may cause a Use-after-Free 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.

Proof-of-concept code is published

Public PoC

Public PoCv4ltonn/CVE-2026-425305 stars
Public PoC0xBlackash/CVE-2026-425303 stars
Public PoCHORKimhab/CVE-2026-42530

Signals come from Exploit-DB, Metasploit, Nuclei and published proof-of-concept repositories. Their absence means nothing was found, not that nothing exists.

Assessment

CVSS: 9.2 (v4.0)
Severity: Critical
EPSS: 6.22% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Public PoC
Published: 17 June 2026
Last updated: 26 October 2026
Affected: F5 · NGINX Open Source
Weakness: CWE-416
Assigner: f5sirt@f5.com

CVSS vectorCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

At the source

References

Community proofs of concept

No community proof of concept yet. If you have one for a published vulnerability and the right to share it, add it below — it will appear here once reviewed.

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