phpMyFAQ before 4.1.2 contains a stored cross-site scripting vulnerability in SvgSanitizer::decodeAllEntities() that limits recursive entity decoding to 5 iterations, allowing attackers to bypass sanitization. Authenticated users with FAQ_EDIT permission can upload malicious SVG files with deeply nested ampersand encoding around numeric HTML entities to reconstruct javascript: URLs, which execute arbitrary JavaScript when clicked by other users viewing the uploaded SVG.

Affected: Packagist: phpmyfaq/phpmyfaq, Packagist: thorsten/phpmyfaq

## Summary

The `SvgSanitizer::decodeAllEntities()` method limits recursive entity decoding to 5 iterations. By wrapping each character of `javascript` in an `href` attribute value with 5 levels of `&` encoding around numeric HTML entities (e.g., `j` for `j`), an attacker can bypass both `isSafe()` detection and `sanitize()` removal. The uploaded SVG is served from the application origin with `image/svg+xml` content type, and the browser's XML parser fully decodes the remaining `&#NNN;` entities, resulting in a clickable `javascript:` link that executes arbitrary JavaScript.

## Details

**Root cause:** `decodeAllEntities()` at `phpmyfaq/src/phpMyFAQ/Helper/SvgSanitizer.php:223-249` limits entity decoding to `maxIterations=5`. Each iteration: (1) decodes `&#NNN;` numeric entities, (2) decodes `&#xHH;` hex entities, (3) calls `html_entity_decode()` which resolves one level of `&` → `&`. With 5 levels of `&` wrapping, all 5 iterations are consumed unwinding the `&` nesting, leaving the final `&#NNN;` numeric entities unresolved.

**Code path:**

1. Authenticated user with `FAQ_EDIT` permission uploads SVG via `POST /admin/api/content/images` (`ImageController::upload()` at line 39) 2. File extension is `svg` → `SvgSanitizer::isSafe()` called (line 114) 3. `isSafe()` calls `decodeAllEntities()` — 5 iterations resolve `&` nesting but leave `ja...` (numeric entities for `javascript`) 4. Pattern matching at line 47 (`/href\s*=\…