Use-after-Free in NGINX Open Source HTTP/3 QUIC Module

Publication date: 2026-06-17

Last updated on: 2026-07-02

Assigner: F5 Networks

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.

CVSS Scores

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Meta Information

Published

2026-06-17

Last Modified

2026-07-02

Generated

2026-07-08

AI Q&A

2026-06-17

EPSS Evaluated

2026-07-06

NVD

CVE-2026-42530

EUVD

EUVD-2026-37717

Affected Vendors & Products

Vendor	Product	Version / Range
f5	nginx_gateway_fabric	From 1.3.0 (inc) to 1.6.2 (inc)
f5	nginx_ingress_controller	From 3.5.0 (inc) to 3.7.2 (inc)
f5	nginx_instance_manager	From 2.17.0 (inc) to 2.22.0 (inc)
f5	nginx_gateway_fabric	From 2.0.0 (inc) to 2.6.4 (exc)
f5	nginx_ingress_controller	From 5.0.0 (inc) to 5.5.1 (exc)
f5	nginx_ingress_controller	4.0.0
f5	nginx_ingress_controller	4.0.1
f5	nginx_open_source	From 1.31.0 (inc) to 1.31.2 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-416	The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Attack-Flow Graph

Impact Analysis

The impact of this vulnerability includes potential denial of service due to the NGINX worker process restarting unexpectedly. Additionally, on systems without effective ASLR protection, attackers may gain the ability to execute arbitrary code, which could lead to full system compromise.

Executive Summary

This vulnerability exists in the ngx_http_v3_module of NGINX Open Source when configured to use the HTTP/3 QUIC module. A remote unauthenticated attacker can exploit this by sending a specially crafted HTTP/3 session that reopens a QPACK encoder stream. This can lead to a Use-after-Free condition in the NGINX worker process, causing the process to restart. In some cases, attackers may also be able to execute code on systems where Address Space Layout Randomization (ASLR) is disabled or can be bypassed.

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