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.

According to its banner, the version of Nginx running on the remote host is prior to 1.30.4 or 1.31.x prior to 1.31.3. It is, therefore, affected by multiple vulnerabilities:

- A heap-based buffer overflow vulnerability exists in the map directive when regex matching is used and a string expression references the map's regex capture variables before referencing the map output variable, or when a non-cacheable variable is used in a string expression under certain conditions. An unauthenticated attacker can exploit this to cause a denial of service or potential code execution on systems with ASLR disabled. (CVE-2026-42533)

- An uninitialized memory access vulnerability exists in the ngx_http_slice_module module when the slice directive and unnamed regex captures are configured or when a background cache update occurs. An unauthenticated attacker can exploit this to cause limited disclosure of memory or a restart of the NGINX worker process. (CVE-2026-60005)

- A use-after-free vulnerability exists in the ngx_http_ssi_module module when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. An attacker with man-in-the-middle ability to control responses from an upstream server can exploit this to cause limited modification of memory or a restart of the NGINX worker process. (CVE-2026-56434)

Note that the scanner has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-56434)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
115314	Nginx < 1.30.4 Multiple Vulnerabilities	Web App Scanning	Component Vulnerability	critical
115313	Nginx 1.31.x < 1.31.3 Multiple Vulnerabilities	Web App Scanning	Component Vulnerability	critical
327357	Linux Distros Unpatched Vulnerability : CVE-2026-56434	Nessus	Misc.	high

Detections

Analytics

CVE-2026-56434

high

Tenable Plugins

critical

critical

high