In Node.js including 6.x before 6.17.0, 8.x before 8.15.1, 10.x before 10.15.2, and 11.x before 11.10.1, an attacker can cause a Denial of Service (DoS) by establishing an HTTP or HTTPS connection in keep-alive mode and by sending headers very slowly. This keeps the connection and associated resources alive for a long period of time. Potential attacks are mitigated by the use of a load balancer or other proxy layer. This vulnerability is an extension of CVE-2018-12121, addressed in November and impacts all active Node.js release lines including 6.x before 6.17.0, 8.x before 8.15.1, 10.x before 10.15.2, and 11.x before 11.10.1.

Node.js: All versions prior to Node.js 6.15.0, 8.14.0, 10.14.0 and 11.3.0: Hostname spoofing in URL parser for javascript protocol: If a Node.js application is using url.parse() to determine the URL hostname, that hostname can be spoofed by using a mixed case "javascript:" (e.g. "javAscript:") protocol (other protocols are not affected). If security decisions are made about the URL based on the hostname, they may be incorrect.

Node.js: All versions prior to Node.js 6.15.0, 8.14.0, 10.14.0 and 11.3.0: Slowloris HTTP Denial of Service: An attacker can cause a Denial of Service (DoS) by sending headers very slowly keeping HTTP or HTTPS connections and associated resources alive for a long period of time.

Node.js: All versions prior to Node.js 6.15.0, 8.14.0, 10.14.0 and 11.3.0: Denial of Service with large HTTP headers: By using a combination of many requests with maximum sized headers (almost 80 KB per connection), and carefully timed completion of the headers, it is possible to cause the HTTP server to abort from heap allocation failure. Attack potential is mitigated by the use of a load balancer or other proxy layer.

Node.js: All versions prior to Node.js 6.15.0 and 8.14.0: HTTP request splitting: If Node.js can be convinced to use unsanitized user-provided Unicode data for the `path` option of an HTTP request, then data can be provided which will trigger a second, unexpected, and user-defined HTTP request to made to the same server.

Simultaneous Multi-threading (SMT) in processors can enable local users to exploit software vulnerable to timing attacks via a side-channel timing attack on 'port contention'.

In all versions of Node.js prior to 6.14.4, 8.11.4 and 10.9.0 when used with UCS-2 encoding (recognized by Node.js under the names `'ucs2'`, `'ucs-2'`, `'utf16le'` and `'utf-16le'`), `Buffer#write()` can be abused to write outside of the bounds of a single `Buffer`. Writes that start from the second-to-last position of a buffer cause a miscalculation of the maximum length of the input bytes to be written.

Calling Buffer.fill() or Buffer.alloc() with some parameters can lead to a hang which could result in a Denial of Service. In order to address this vulnerability, the implementations of Buffer.alloc() and Buffer.fill() were updated so that they zero fill instead of hanging in these cases. All versions of Node.js 6.x (LTS "Boron"), 8.x (LTS "Carbon"), and 9.x are vulnerable. All versions of Node.js 10.x (Current) are NOT vulnerable.

All versions of Node.js 8.x, 9.x, and 10.x are vulnerable and the severity is HIGH. An attacker can cause a denial of service (DoS) by causing a node server providing an http2 server to crash. This can be accomplished by interacting with the http2 server in a manner that triggers a cleanup bug where objects are used in native code after they are no longer available. This has been addressed by updating the http2 implementation.

Node.js had a bug in versions 8.X and 9.X which caused buffers to not be initialized when the encoding for the fill value did not match the encoding specified. For example, 'Buffer.alloc(0x100, "This is not correctly encoded", "hex");' The buffer implementation was updated such that the buffer will be initialized to all zeros in these cases.

Node.js was affected by OpenSSL vulnerability CVE-2017-3737 in regards to the use of SSL_read() due to TLS handshake failure. The result was that an active network attacker could send application data to Node.js using the TLS or HTTP2 modules in a way that bypassed TLS authentication and encryption.

Node.js before 4.8.5, 6.x before 6.11.5, and 8.x before 8.8.0 allows remote attackers to cause a denial of service (uncaught exception and crash) by leveraging a change in the zlib module 1.2.9 making 8 an invalid value for the windowBits parameter.