CVE-2026-42530: NGINX Open-Source ngx_http_v3_module vulnerability

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 6.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-17 · updated 2026-10-26
Weakness: CWE-416

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 products

F5 NGINX Gateway Fabric: from 1.3.0 through 1.6.2; from 2.0.0 before 2.6.4 — fixed in 2.6.4
F5 NGINX Ingress Controller: from 3.5.0 through 3.7.2; from 5.0.0 before 5.5.1; 4.0.0, 4.0.1 — fixed in 5.5.1
F5 NGINX Instance Manager: from 2.17.0 through 2.22.0
F5 NGINX Open Source: from 1.31.0 before 1.31.2 — fixed in 1.31.2

How to fix

Upgrade to a fixed version: F5 NGINX Gateway Fabric 2.6.4; F5 NGINX Ingress Controller 5.5.1; F5 NGINX Open Source 1.31.2. Check the vendor advisory for mitigations.

References

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