GHSA-hmr5-2xcr-v8pp Symfony Vulnerable to stored XSS in WebProfiler CodeExtension::fileExcerpt() — Unescaped Non-PHP File Rendering

• Packagist symfony/symfony: >= 6.4.24, < 6.4.40 → fixed in 6.4.40 • Packagist symfony/symfony: >= 7.2.9, < 7.4.12 → fixed in 7.4.12 • Packagist symfony/symfony: >= 8.0.0, < 8.0.12 → fixed in 8.0.12 • Packagist symfony/twig-bridge: >= 6.4.24, < 6.4.40 → fixed in 6.4.40 • Packagist symfony/web-profiler-bundle: >= 7.2.9, < 7.4.12 → fixed in 7.4.12 • Packagist symfony/web-profiler-bundle: >= 8.0.0, < 8.0.12 → fixed in 8.0.12

Description Symfony's profiler, a development only debug UI, renders source-code excerpts on several pages using Twig's custom `file_excerpt` filter. This filter renders PHP files via `highlight_string()` (which escapes HTML), but renders non-PHP files by splitting on `\n` and interpolating each line directly into `{$line}` with no escaping. An attacker who can write arbitrary bytes into any file under the project root (including e.g. `var/log/dev.log`), achieves stored XSS against any developer who later opens that file in the profiler. Resolution The `file_excerpt` filter now properly escapes each line of non-PHP files using `htmlspecialchars()` before concatenating them. The patch for this issue is available here for branch 6.4. Credits Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.