decode-uri-component: Denial of service via quadratic replacement of percent-encoded runs
decode-uri-component provides a more robust alternative to decodeURIComponent. Prior to 0.5.1, decodeUriComponent in index.js falls back to customDecodeURIComponent after native decoding throws, and the fallback collects every distinct percent-encoded run before performing a full-string regular-expression replacement for each entry. Malformed input containing many distinct runs can therefore make both the number of replacements and the scanned input length grow together, causing quadratic CPU consumption and blocking the Node.js event loop; request-body inputs can reach the demonstrated size, while ordinary URL header limits reduce the practi
decode-uri-component through 0.4.1 is vulnerable to denial of service. The decode() function splits input on '%' producing N tokens and calls decodeComponents(), exhibiting super-linear parsing time: 200 '%ab' tokens takes approximately 0.7s, 700 tokens approximately 6s, and 1400 tokens approximately 33s. An attacker can cause significant CPU consumption and event-loop blocking via crafted input.