Fastify rewriteRequestHeaders() Unauthenticated Access Modification

The vulnerability of the rewriteRequestHeaders function in the Fastify framework, a Node.js software platform, is related to HTTP request processing flaws. Exploiting this vulnerability can allow an attacker, operating remotely, to gain unauthorized access and modify protected information...

CVE-2026-33805

@fastify/reply-from v12.6.1 and earlier and @fastify/http-proxy v11.4.3 and earlier process the client's Connection header after the proxy has added its own headers via rewriteRequestHeaders. This allows attackers to retroactively strip proxy-added headers from upstream requests by listing them i...