tmp: Path Traversal via unsanitized prefix/postfix enables directory escape

tmp is a temporary file and directory creator for node.js. Prior to 0.2.6, the tmp npm package contains a path traversal vulnerability that allows escaping the intended temporary directory when untrusted data flows into the prefix, postfix, or dir options. By embedding traversal sequences (e.g., ../) or path separators in these parameters, attackers can cause files to be created outside the configured temporary base directory at attacker-controlled locations with the privileges of the running process. This vulnerability affects applications that pass user-controlled data to tmp's file/directory creation functions without proper input sanitization. This vulnerability is fixed in 0.2.6.