CVE-2026-33035: Wwbn/avideo Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-wfq5-qgqp-hvhv",
  "modified" : "2026-03-20T21:22:24Z",
  "published" : "2026-03-17T20:05:23Z",
  "aliases" : [ "CVE-2026-33035" ],
  "summary" : "Unauthenticated Reflected XSS via innerHTML in AVideo",
  "details" : "## Summary\n\nAVideo contains a reflected XSS vulnerability that allows unauthenticated attackers to execute arbitrary JavaScript in a victim's browser. User input from a URL parameter flows through PHP's `json_encode()` into a JavaScript function that renders it via `innerHTML`, bypassing encoding and achieving full script execution.\n\n\n## Root Cause\nThe vulnerability is caused by two issues working together:\n\n### 1. Source: Unescaped user input passed to JavaScript (videoNotFound.php)\n\n**File:** `view/videoNotFound.php` line 49\n\n```php\nif (!empty($_REQUEST['404ErrorMsg'])) {\n    echo 'avideoAlertInfo(' . json_encode($_REQUEST['404ErrorMsg']) . ');';\n}\n```\n\nPHP's `json_encode()` with default flags only escapes quotes (`\"` → `\\\"`) and backslashes. It does **NOT** escape HTML special characters (`<`, `>`, `/`). The resulting string contains raw HTML tags that are passed directly to JavaScript.\n\n### 2. Sink: innerHTML renders HTML tags as executable DOM (script.js)\n\n**File:** `view/js/script.js`\n\n```javascript\nfunction avideoAlertInfo(msg) {            // line ~1891\n    avideoAlert(\"\", msg, 'info');           // calls ↓\n}\n\nfunction avideoAlert(title, msg, type) {   // line ~1270\n    avideoAlertHTMLText(title, msg, type);  // calls ↓\n}\n\nfunction avideoAlertHTMLText(title, msg, type) {  // line ~1451\n    var span = document.createElement(\"span\");\n    span.innerHTML = msg;                  // line 1464 — XSS SINK\n    swal({ content: span });\n}\n```\n\n`innerHTML` parses the string as HTML. Any `<img>`, `<svg>`, or other HTML tags with event handlers are instantiated as real DOM elements, triggering JavaScript execution.\n\n### Data Flow\n\n```\nURL parameter (?404ErrorMsg=PAYLOAD)\n    → $_REQUEST['404ErrorMsg']\n    → json_encode()          ← does NOT escape < > /\n    → avideoAlertInfo()\n    → avideoAlert()\n    → avideoAlertHTMLText()\n    → span.innerHTML = msg   ← renders HTML tags, executes JS\n```\n\n---\n\n## Proof of Concept\n```\nhttps://localhost/view/videoNotFound.php?404ErrorMsg=<img src=x onerror=alert(document.domain)>\n```\n<img width=\"1918\" height=\"1035\" alt=\"image\" src=\"https://github.com/user-attachments/assets/20077ce2-5b49-4bd3-a7df-ab48be786cc1\" />\n\nThe page renders:\n```javascript\navideoAlertInfo(\"<img src=x onerror=alert(document.domain)>\");\n```\n\nWhich flows to `span.innerHTML = \"<img src=x onerror=alert(document.domain)>\"`. The browser creates an `<img>` element, `src=x` fails to load, `onerror` fires `alert(document.domain)`.\n\n## Affected Code\n\n| File | Line | Issue |\n|------|------|-------|\n| `view/videoNotFound.php` | 49 | `json_encode()` does not escape `<` `>` for HTML context |\n| `view/js/script.js` | 1464 | `span.innerHTML = msg` renders user input as HTML |\n| `view/js/script.js` | 1282 | `span.innerHTML = msg` in `avideoAlertWithCookie()` |\n| `view/js/script.js` | 1335 | `span.innerHTML = __(msg,true)` in `avideoConfirm()` |\n| `view/js/script.js` | 1358 | `span.innerHTML = msg` in `avideoAlertOnceForceConfirm()` |\n\nThe `innerHTML` sink exists in 4 functions. Any future code that passes user input to `avideoAlertInfo()`, `avideoAlertWarning()`, `avideoAlertDanger()`, or `avideoAlertSuccess()` will create additional XSS vectors.\n\n\n## Remediation\n\n### Fix 1: Escape HTML in PHP (source fix)\n\n```php\n// view/videoNotFound.php line 49\n// BEFORE (vulnerable):\necho 'avideoAlertInfo(' . json_encode($_REQUEST['404ErrorMsg']) . ');';\n\n// AFTER (fixed):\necho 'avideoAlertInfo(' . json_encode($_REQUEST['404ErrorMsg'], JSON_HEX_TAG | JSON_HEX_AMP) . ');';\n```\n\n`JSON_HEX_TAG` converts `<` → `\\u003C` and `>` → `\\u003E`, preventing HTML injection.\n\n### Fix 2: Use textContent instead of innerHTML (sink fix, recommended)\n\n```javascript\n// view/js/script.js - all alert functions\n// BEFORE (vulnerable):\nspan.innerHTML = msg;\n\n// AFTER (fixed):\nspan.textContent = msg;\n```\n\n`textContent` treats the string as plain text — HTML tags are displayed literally, never parsed or executed.\n\n### Fix 3: Add Content-Security-Policy header (defense in depth)\n\n```\nContent-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'\n```\n\n## Impact\n\n- **Session hijacking** — steal `PHPSESSID` cookie (not HttpOnly by default)\n- **Account takeover** — use stolen session to change password or email\n- **Phishing** — inject a realistic login form inside the SweetAlert modal\n- **Worm propagation** — inject self-spreading payloads via comments/messages\n- **Admin compromise** — send crafted link to admin, steal session, gain full control",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "wwbn/avideo"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "25.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/WWBN/AVideo/security/advisories/GHSA-wfq5-qgqp-hvhv"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33035"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/WWBN/AVideo/commit/cca6196f4072cb9acc39b1030fb8fb1702b4f69b"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/WWBN/AVideo"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-17T20:05:23Z",
    "nvd_published_at" : "2026-03-20T05:16:16Z"
  }
}