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F5 has released security updates to address two critical security flaws in NGINX Open Source that could be exploited to achieve code execution on affected systems. The vulnerabilities are listed below - CVE-2026-42530 (CVSS v4 score: 9.2) - A use-after-free vulnerability in the ngx_http_v3_module that could be triggered by a remote unauthenticated attacker when NGINX Open Source is configured to use the HTTP/3 QUIC module to reopen a QPACK encoder stream by means of a specially crafted HTTP/3 session, and execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. CVE-2026-42055 (CVSS v4 score: 9.2) - A heap-based buffer overflow vulnerability in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules that could be triggered by a remote unauthenticated attacker when the proxy_http_version to 2 or grpc_pass directives are used to proxy HTTP/2 traffic, the ignore_invalid_headers directive is set to off, and the ...

Cybersecurity researchers have discovered a remote denial-of-service exploit that affects major web servers, including NGINX, Apache HTTPD, Microsoft IIS, Envoy, and Cloudflare Pingora. The vulnerability has been codenamed HTTP/2 Bomb by Calif. "The vulnerable behavior exists in each server's default HTTP/2 configuration," the company said, adding it was discovered by OpenAI Codex by chaining together two known techniques: a compression bomb and a Slowloris -style hold. "The bomb targets HPACK, HTTP/2's header compression scheme: one byte on the wire becomes one full header allocation on the server, repeated thousands of times per request," Calif added. "The hold is a zero-byte flow-control window that keeps the server from ever freeing any of it." HPACK is a dedicated header compression algorithm for HTTP/2 used for compressing request and response metadata using Huffman encoding that results in an average reduction of 30% in header siz...

Cybersecurity researchers have disclosed multiple security vulnerabilities impacting NGINX Plus and NGINX Open, including a critical flaw that remained undetected for 18 years. The vulnerability, discovered by depthfirst , is a heap buffer overflow issue impacting ngx_http_rewrite_module (CVE-2026-42945, CVSS v4 score: 9.2) that could allow an attacker to achieve remote code execution or cause a denial-of-service (DoS) with crafted requests. It has been codenamed NGINX Rift . "NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module," F5 said in an advisory released Wednesday. "This vulnerability exists when the rewrite directive is followed by a rewrite, if, or set directive and an unnamed Perl-Compatible Regular Expression (PCRE) capture (for example, $1, $2) with a replacement string that includes a question mark (?)." "An unauthenticated attacker, along with conditions beyond its control, can exploit this vulnerabili...