Nginx 1.31.x < 1.31.3 Multiple Vulnerabilities

critical Web App Scanning Plugin ID 115313

Synopsis

Description

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.