Node.js versions before 10.23.1, 12.20.1, 14.15.4, 15.5.1 allow two copies of a header field in an HTTP request (for example, two Transfer-Encoding header fields). In this case, Node.js identifies the first header field and ignores the second. This can lead to HTTP Request Smuggling.

A flaw in Node.js’s Permissions model allows attackers to bypass `--allow-fs-read` and `--allow-fs-write` restrictions using crafted relative symlink paths. By chaining directories and symlinks, a script granted access only to the current directory can escape the allowed path and read sensitive files. This breaks the expected isolation guarantees and enables arbitrary file read/write, leading to potential system compromise. This vulnerability affects users of the permission model on Node.js v20, v22, v24, and v25.

The Update method in src/node_http_parser.cc in Node.js before 0.6.17 and 0.7 before 0.7.8 does not properly check the length of a string, which allows remote attackers to obtain sensitive information (request header contents) and possibly spoof HTTP headers via a zero length string.

A weak randomness in WebCrypto keygen vulnerability exists in Node.js 18 due to a change with EntropySource() in SecretKeyGenTraits::DoKeyGen() in src/crypto/crypto_keygen.cc. There are two problems with this: 1) It does not check the return value, it assumes EntropySource() always succeeds, but it can (and sometimes will) fail. 2) The random data returned byEntropySource() may not be cryptographically strong and therefore not suitable as keying material.