NGINX Open Source
CVE-2026-42530
CRITICAL
Severity by source
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Network-reachable HTTP/3 listener with no auth or user interaction (AV:N/PR:N/UI:N); AC:H reflects vendor-stated conditions beyond attacker control and ASLR dependency for RCE; full C/I/A on worker compromise.
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from Vendor (f5).
CVSS VectorVendor: f5
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
7DescriptionCVE.org
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.
Articles & Coverage 3
AnalysisAI
Use-after-free in NGINX Open Source's ngx_http_v3_module allows remote unauthenticated attackers to crash worker processes and potentially execute arbitrary code on hosts where HTTP/3 QUIC is enabled. Exploitation requires a specially crafted HTTP/3 session that reopens a QPACK encoder stream, with code execution contingent on ASLR being disabled or bypassed; no public exploit identified at time of analysis, though SSVC technical impact is rated total.
Technical ContextAI
The flaw resides in the ngx_http_v3_module, which implements HTTP/3 over QUIC and uses QPACK (RFC 9204) for header compression. QPACK relies on a dedicated unidirectional encoder stream from client to server to maintain a dynamic table of header field representations; per spec there must only ever be one encoder stream per connection. By inducing the server to reopen this stream mid-session, the attacker triggers CWE-416 (Use-After-Free) inside the NGINX worker, where a freed QPACK decoder/stream context is dereferenced. The affected CPE is cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:*, covering supported NGINX Open Source branches that ship the HTTP/3 module; F5 explicitly excludes End-of-Technical-Support versions from evaluation.
RemediationAI
Patch available per vendor advisory: upgrade NGINX Open Source to the fixed branch released by F5 as detailed in https://my.f5.com/manage/s/article/K000161616 (cite the exact fix version from that advisory for change-management). If immediate patching is not possible, the most effective workaround is to disable HTTP/3 by removing the 'quic' parameter from any 'listen ... quic' directives and reloading NGINX, which fully removes the vulnerable code path at the cost of losing HTTP/3 client support and forcing fallback to HTTP/2 or HTTP/1.1. As a hardening measure, ensure ASLR is enabled kernel-wide (kernel.randomize_va_space=2 on Linux) and that NGINX binaries and loaded modules are PIE-compiled, which neutralizes the code-execution path described by the vendor and reduces the bug to a worker restart denial-of-service; restricting UDP/443 ingress at upstream load balancers or firewalls to trusted networks is an additional compensating control where HTTP/3 must remain enabled.
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Same weakness CWE-416 – Use After Free
View allSame technique Use After Free
View allVendor StatusVendor
SUSE
Severity: Important| Product | Status |
|---|---|
| openSUSE Tumbleweed | Fixed |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Server 16.0 | Not-Affected |
| SUSE Linux Enterprise Server 16.1 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Not-Affected |
| SUSE Linux Enterprise Server for SAP applications 16.0 | Not-Affected |
| SUSE Linux Enterprise Server for SAP applications 16.1 | Not-Affected |
| openSUSE Leap 16.0 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Not-Affected |
| SUSE Manager Proxy 4.3 | Not-Affected |
| SUSE Manager Proxy LTS 4.3 | Not-Affected |
| SUSE Manager Retail Branch Server 4.3 | Not-Affected |
| SUSE Manager Retail Branch Server LTS 4.3 | Not-Affected |
| SUSE Manager Server 4.3 | Not-Affected |
| SUSE Manager Server LTS 4.3 | Not-Affected |
| SUSE CaaS Platform 4.0 | Not-Affected |
| SUSE Enterprise Storage 6 | Not-Affected |
| SUSE Enterprise Storage 7 | Not-Affected |
| SUSE Enterprise Storage 7.1 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Module for Server Applications 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | Not-Affected |
| SUSE Manager Proxy 4.0 | Not-Affected |
| SUSE Manager Proxy 4.1 | Not-Affected |
| SUSE Manager Proxy 4.2 | Not-Affected |
| SUSE Manager Retail Branch Server 4.0 | Not-Affected |
| SUSE Manager Retail Branch Server 4.1 | Not-Affected |
| SUSE Manager Retail Branch Server 4.2 | Not-Affected |
| SUSE Manager Server 4.0 | Not-Affected |
| SUSE Manager Server 4.1 | Not-Affected |
| SUSE Manager Server 4.2 | Not-Affected |
| openSUSE Leap 15.3 | Not-Affected |
| openSUSE Leap 15.4 | Not-Affected |
| openSUSE Leap 15.5 | Not-Affected |
| openSUSE Leap 15.6 | Not-Affected |
| private-registry/1.2/harbor-portal private-registry/harbor-nginx private-registry/harbor-portal suse/nginx suse/rmt-nginx | Not-Affected |
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