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From 97813ae58d19687f3c61f6355b4307c88908058a Mon Sep 17 00:00:00 2001
From: isaacs <>
Date: Tue, 22 Oct 2013 10:56:03 -0700
Subject: [PATCH] blog: HTTP server DoS vulnerability details
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+title: DoS Vulnerability (fixed in Node v0.8.26 and v0.10.21)
+date: Tue Oct 22 10:42:10 PDT 2013
+slug: cve-2013-4450-http-server-pipeline-flood-dos
+category: vulnerability
+Node.js is vulnerable to a denial of service attack when a client
+sends many pipelined HTTP requests on a single connection, and the
+client does not read the responses from the connection.
+We recommend that anyone using Node.js v0.8 or v0.10 to run HTTP
+servers in production please update as soon as possible.
+* v0.10.21 <>
+* v0.8.26 <>
+This is fixed in Node.js by pausing both the socket and the HTTP
+parser whenever the downstream writable side of the socket is awaiting
+a drain event. In the attack scenario, the socket will eventually
+time out, and be destroyed by the server. If the "attacker" is not
+malicious, but merely sends a lot of requests and reacts to them
+slowly, then the throughput on that connection will be reduced to what
+the client can handle.
+There is no change to program semantics, and except in the
+pathological cases described, no changes to behavior.
+If upgrading is not possible, then putting an HTTP proxy in front of
+the Node.js server can mitigate the vulnerability, but only if the
+proxy parses HTTP and is not itself vulnerable to a pipeline flood
+For example, nginx will prevent the attack (since it closes
+connections after 100 pipelined requests by default), but HAProxy in
+raw TCP mode will not (since it proxies the TCP connection without
+regard for HTTP semantics).
+This addresses CVE-2013-4450.
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