{"id":18924,"date":"2026-10-21T20:17:39","date_gmt":"2026-10-21T17:17:39","guid":{"rendered":"https:\/\/www.hyyat.com\/knowledgebase\/xss-cross-site-scripting\/"},"modified":"2026-10-21T20:17:53","modified_gmt":"2026-10-21T17:17:53","password":"","slug":"xss-cross-site-scripting","status":"publish","type":"docs","link":"https:\/\/www.hyyat.com\/en\/knowledgebase\/xss-cross-site-scripting\/","title":{"rendered":"What Is an XSS Attack? Cross-Site Scripting Explained and How to Prevent It"},"content":{"rendered":"
\n
In short<\/b>XSS (cross-site scripting) is an attack where someone places JavaScript code into a page on your site through a comment, form or link. When a visitor opens the page, the code runs in their browser and may steal their login session, redirect them or show a fake form. Protection: escape everything visitors write before displaying it, keep plugins updated and add security headers such as CSP.<\/div>\n
\"XSS<\/figure>\n

How does the attack work?<\/h2>\n

In XSS the attacker does not target the server directly; they target your visitors<\/strong>. They use any place where your site displays text written by someone else without cleaning it, such as comments, search results or profiles, and put code there instead of text.<\/p>\n

Types of XSS<\/h2>\n
\n\n\n\n\n\n\n\n
Type<\/th>\nHow it happens<\/th>\nExample<\/th>\n<\/tr>\n<\/thead>\n
Stored<\/td>\nThe code is saved in the database and shown to everyone who opens the page.<\/td>\nA comment or product review containing a script.<\/td>\n<\/tr>\n
Reflected<\/td>\nThe code is in the link itself and runs only for whoever clicks it.<\/td>\nA crafted search link emailed to the victim.<\/td>\n<\/tr>\n
DOM-based<\/td>\nThe page\u2019s own JavaScript writes a value from the URL into the page unescaped.<\/td>\nA script that reads part of the URL and displays it.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

What can the attacker do?<\/h2>\n
\n
1<\/i>Hijack sessions<\/b>If a site admin opens the infected page, the attacker may take over their session.<\/span><\/div>\n
2<\/i>Redirect visitors<\/b>Send them to scam sites or ads.<\/span><\/div>\n
3<\/i>Fake forms<\/b>Show a fake login or payment form inside your real page.<\/span><\/div>\n
4<\/i>Hurt your reputation<\/b>Your site may be flagged as dangerous. Read fixing the Google warning<\/a>.<\/span><\/div>\n<\/div>\n

How to protect your site<\/h2>\n
    \n
  1. Update plugins and themes:<\/b> Many WordPress XSS flaws are in old form, slider and comment plugins.<\/li>\n
  2. Developers: escape output:<\/b> Display any visitor text only after escaping it. In WordPress use esc_html()<\/code>, esc_attr()<\/code> and esc_url()<\/code>, and in PHP use htmlspecialchars()<\/code>.<\/li>\n
  3. Moderate comments:<\/b> Turn on comment moderation, and disable comments where you do not need them.<\/li>\n
  4. Add security headers:<\/b> A CSP policy lists the allowed script sources, making injected code harder to run. Read security headers<\/a>.<\/li>\n
  5. Protect cookies:<\/b> WordPress makes its login cookies HttpOnly so JavaScript cannot read them. In custom code, use HttpOnly and Secure too.<\/li>\n
  6. Use a web application firewall:<\/b> ModSecurity<\/a> rules stop known XSS patterns in requests.<\/li>\n<\/ol>\n
    <?php \/\/ Wrong\necho $_GET['name'];\n\n\/\/ Right\necho esc_html($_GET['name'] ?? '');<\/pre>\n
    \n
    How Hyyat Host protects your site<\/h2>\n