Keep-alive HTTP and HTTPS connections can remain open and inactive for up to 2 minutes in Node.js 6.16.0 and earlier. Node.js 8.0.0 introduced a dedicated server.keepAliveTimeout which defaults to 5 seconds. The behavior in Node.js 6.16.0 and earlier is a potential Denial of Service (DoS) attack vector. Node.js 6.17.0 introduces server.keepAliveTimeout and the 5-second default.

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.

If an application encounters a fatal protocol error and then calls SSL_shutdown() twice (once to send a close_notify, and once to receive one) then OpenSSL can respond differently to the calling application if a 0 byte record is received with invalid padding compared to if a 0 byte record is received with an invalid MAC. If the application then behaves differently based on that in a way that is detectable to the remote peer, then this amounts to a padding oracle that could be used to decrypt data. In order for this to be exploitable "non-stitched" ciphersuites must be in use. Stitched ciphersuites are optimised implementations of certain commonly used ciphersuites. Also the application must call SSL_shutdown() twice even if a protocol error has occurred (applications should not do this but some do anyway). Fixed in OpenSSL 1.0.2r (Affected 1.0.2-1.0.2q).

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: Debugger port 5858 listens on any interface by default: When the debugger is enabled with `node --debug` or `node debug`, it listens to port 5858 on all interfaces by default. This may allow remote computers to attach to the debug port and evaluate arbitrary JavaScript. The default interface is now localhost. It has always been possible to start the debugger on a specific interface, such as `node --debug=localhost`. The debugger was removed in Node.js 8 and replaced with the inspector, so no versions from 8 and later are vulnerable.

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'.

The OpenSSL DSA signature algorithm has been shown to be vulnerable to a timing side channel attack. An attacker could use variations in the signing algorithm to recover the private key. Fixed in OpenSSL 1.1.1a (Affected 1.1.1). Fixed in OpenSSL 1.1.0j (Affected 1.1.0-1.1.0i). Fixed in OpenSSL 1.0.2q (Affected 1.0.2-1.0.2p).

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.

During key agreement in a TLS handshake using a DH(E) based ciphersuite a malicious server can send a very large prime value to the client. This will cause the client to spend an unreasonably long period of time generating a key for this prime resulting in a hang until the client has finished. This could be exploited in a Denial Of Service attack. Fixed in OpenSSL 1.1.0i-dev (Affected 1.1.0-1.1.0h). Fixed in OpenSSL 1.0.2p-dev (Affected 1.0.2-1.0.2o).

The Node.js inspector, in 6.x and later is vulnerable to a DNS rebinding attack which could be exploited to perform remote code execution. An attack is possible from malicious websites open in a web browser on the same computer, or another computer with network access to the computer running the Node.js process. A malicious website could use a DNS rebinding attack to trick the web browser to bypass same-origin-policy checks and to allow HTTP connections to localhost or to hosts on the local network. If a Node.js process with the debug port active is running on localhost or on a host on the local network, the malicious website could connect to it as a debugger, and get full code execution access.

The HTTP parser in all current versions of Node.js ignores spaces in the `Content-Length` header, allowing input such as `Content-Length: 1 2` to be interpreted as having a value of `12`. The HTTP specification does not allow for spaces in the `Content-Length` value and the Node.js HTTP parser has been brought into line on this particular difference. The security risk of this flaw to Node.js users is considered to be VERY LOW as it is difficult, and may be impossible, to craft an attack that makes use of this flaw in a way that could not already be achieved by supplying an incorrect value for `Content-Length`. Vulnerabilities may exist in user-code that make incorrect assumptions about the potential accuracy of this value compared to the actual length of the data supplied. Node.js users crafting lower-level HTTP utilities are advised to re-check the length of any input supplied after parsing is complete.

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.

There is an overflow bug in the AVX2 Montgomery multiplication procedure used in exponentiation with 1024-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH1024 are considered just feasible, because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be significant. However, for an attack on TLS to be meaningful, the server would have to share the DH1024 private key among multiple clients, which is no longer an option since CVE-2016-0701. This only affects processors that support the AVX2 but not ADX extensions like Intel Haswell (4th generation). Note: The impact from this issue is similar to CVE-2017-3736, CVE-2017-3732 and CVE-2015-3193. OpenSSL version 1.0.2-1.0.2m and 1.1.0-1.1.0g are affected. Fixed in OpenSSL 1.0.2n. Due to the low severity of this issue we are not issuing a new release of OpenSSL 1.1.0 at this time. The fix will be included in OpenSSL 1.1.0h when it becomes available. The fix is also available in commit e502cc86d in the OpenSSL git repository.

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.