CWE-86 (Web页面标识中非法字符转义处理不恰当) — Vulnerability Class 6

CWE-86 represents a critical input validation weakness where software fails to properly neutralize invalid characters or byte sequences within identifiers such as tag names and URI schemes. Attackers typically exploit this flaw by injecting obfuscated payloads, like null bytes or encoded characters, to bypass security filters. For instance, a developer might attempt to block the "javascript:" protocol, but an attacker can circumvent this check using "java%00script," causing the browser to interpret the malicious script as valid. This discrepancy often leads to unintended control implications, including cross-site scripting or unauthorized command execution. To prevent such vulnerabilities, developers must implement rigorous input sanitization that strictly validates and encodes all user-supplied data before processing. Utilizing established security libraries and adhering to strict allow-listing principles ensures that only expected character sets are accepted, effectively neutralizing potential injection vectors before they reach the application logic.