CWE-80 (Web页面中脚本相关HTML标签转义处理不恰当(基本跨站脚本)) — Vulnerability Class 443

CWE-80 represents a critical input validation weakness where applications fail to properly sanitize user-supplied data before rendering it in web pages. This flaw allows attackers to inject malicious scripts, typically JavaScript, into the HTML content viewed by other users. Exploitation usually occurs when an attacker crafts a malicious URL or form input containing script tags, which the vulnerable application then executes in the victim’s browser without proper filtering. This can lead to severe consequences such as session hijacking, credential theft, or defacement. To mitigate this risk, developers must implement robust output encoding strategies, ensuring that all special characters like angle brackets and ampersands are converted into their safe HTML entity equivalents. Additionally, employing Content Security Policy headers and utilizing modern frameworks with built-in escaping mechanisms further reduces the attack surface by preventing the execution of unauthorized scripts.