Three vulnerabilities in nginx require immediate patching: a high-severity flaw (CVE-2026-42533, CVSS 8.1) in regex map directives allowing RCE or DoS, a medium-severity use-after-free (CVE-2026-56434, CVSS 6.5) in the SSI module under specific configurations, and a high-severity information leak/DoS issue (CVE-2026-60005, CVSS 8.2) in the slice module.
It was discovered that nginx incorrectly handled certain map directives using regex matching and capture variables. A remote attacker could use this issue to cause nginx to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2026-42533) It was discovered that nginx had a use-after-free vulnerability in the ngx_http_ssi_module module when configured with Server-Side Includes, proxy_pass, and proxy buffering disabled directives. An attacker able to intercept traffic and control responses from an upstream server could possibly use this issue to cause nginx to crash, resulting in a denial of service. (CVE-2026-56434) It was discovered that nginx incorrectly handled certain requests in the ngx_http_slice_module module. A remote attacker could possibly use this issue to obtain sensitive information or cause nginx to crash, resulting in a denial of service. (CVE-2026-60005)