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Vulnerability · Published Jun 17, 2026 · Assigned by f5

CVE-2026-42530NGINX Open-Source ngx_http_v3_module vulnerability

High 8.1

In plain English

A high-severity use-after-free in NGINX Open Source from F5. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 6.2% (higher than 94% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.

Severity (CVSS 3.1)8.1High
Exploit odds (30 days)6.2%top 6.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC

Official description

NGINX Open Source has a vulnerability in the ngx_http_v3_module 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:14nginxno fix listedDEBIAN-CVE-2026-42530
Ubuntu:22.04:LTSnginxno fix listedUBUNTU-CVE-2026-42530
Ubuntu:24.04:LTSnginxno fix listedUBUNTU-CVE-2026-42530
Ubuntu:25.10nginxno fix listedUBUNTU-CVE-2026-42530
Ubuntu:26.04:LTSnginxno fix listedUBUNTU-CVE-2026-42530

Affected products (as reported)

VendorProductVersions
F5 NGINX Open Source 1.31.0 – before 1.31.2

Weakness: CWE-416 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References