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CVE-2026-56434— NGINX ngx_http_ssi_module vulnerability

Quick assessment

Affected
F5 NGINX Plus
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

F5 nginx plus是美国F5公司的一款高性能Web服务器和反向代理。 F5 nginx plus存在资源管理错误漏洞，该漏洞源于ngx_http_ssi_module模块问题，当配置SSI、proxy_pass和proxy_buffering off指令时，可能导致未经验证的攻击者通过中间人攻击方式控制上游服务器响应，在工作进程中引发释放后重用漏洞，从而造成内存内容修改或工作进程重启。以下版本受到影响：NGINX Plus 37.0.0.1版本至37.0.3.1之前版本、R36版本至R36 P7之

CVSS 6.5 · Medium EPSS 0.42% · P34

Affected Version Matrix 5

VendorProduct Version RangeStatus
F5 NGINX Open Source 1.31.2< 1.31.3 affected
0.8.11< 1.30.4 affected
F5 NGINX Plus 37.0.0.1< 37.0.3.1 affected
R36< R36 P7 affected
R33< * affected
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I. Basic Information for CVE-2026-56434

Vulnerability Information
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Vulnerability Title
NGINX ngx_http_ssi_module vulnerability
Source: CVE Program / CVE List V5
Vulnerability Description
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
释放后使用
Source: CVE Program / CVE List V5
Vulnerability Title
F5 nginx plus 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
F5 nginx plus是美国F5公司的一款高性能Web服务器和反向代理。 F5 nginx plus存在资源管理错误漏洞，该漏洞源于ngx_http_ssi_module模块问题，当配置SSI、proxy_pass和proxy_buffering off指令时，可能导致未经验证的攻击者通过中间人攻击方式控制上游服务器响应，在工作进程中引发释放后重用漏洞，从而造成内存内容修改或工作进程重启。以下版本受到影响：NGINX Plus 37.0.0.1版本至37.0.3.1之前版本、R36版本至R36 P7之
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
F5 NGINX Plus 37.0.0.1 ~ 37.0.3.1 -
F5 NGINX Open Source 1.31.2 ~ 1.31.3 -

II. Public POCs for CVE-2026-56434

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III. Intelligence Information for CVE-2026-56434

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Other References for CVE-2026-56434 (1)

Same Patch Batch · F5 · 2026-07-15 · 8 CVEs total

CVE-2026-55723 8.3 HIGH NGINX Ingress Controller vulnerability
CVE-2026-60005 8.2 HIGH NGINX ngx_http_slice_module vulnerability
CVE-2026-42533 8.1 HIGH NGINX Map directive and Regex matching vulnerability
CVE-2026-59762 7.5 HIGH BIG-IP HTTP/2 vulnerability
CVE-2026-52865 6.5 MEDIUM NGINX Ingress Controller vulnerability
CVE-2026-60062 6.4 MEDIUM NGINX Agent Vulnerability
CVE-2026-60065 3.7 LOW NGINX Plus ngx_stream_mqtt_filter_module vulnerability

IV. Related Vulnerabilities

Same product: NGINX Plus
Same vendor: F5
Same weakness: CWE-416

V. Comments for CVE-2026-56434

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