CWE-156 (空格转义处理不恰当) — Vulnerability Class 4

CWE-156 represents a critical input validation weakness where software fails to properly neutralize or sanitize whitespace characters received from upstream components before passing them to downstream processes. This vulnerability typically arises when developers assume that spaces, tabs, or other control characters are harmless, allowing attackers to inject unexpected formatting that alters the interpretation of data. Exploitation often involves manipulating command-line arguments, file paths, or structured data formats like XML or JSON, where invisible whitespace can bypass security filters or cause syntax errors that lead to denial of service or code injection. To mitigate this risk, developers must implement strict input validation routines that explicitly define allowed whitespace patterns and sanitize or reject unexpected characters. Utilizing robust parsing libraries that handle whitespace normalization automatically, rather than relying on manual string manipulation, ensures consistent behavior across different environments and prevents downstream components from misinterpreting maliciously crafted input.