CVE-2026-45072

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.4.24 until 6.4.40, 7.4.12, and 8.0.12, the development profiler file_excerpt Twig filter escapes PHP files through highlight_string() but interpolates lines from non-PHP files directly into <code> elements, allowing stored XSS against a developer who opens an attacker-written file such as var/log/dev.log in the profiler. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.4.24 until 6.4.40, 7.4.12, and 8.0.12, the development profiler file_excerpt Twig filter escapes PHP files through highlight_string() but interpolates lines from non-PHP files directly into <code> elements, allowing stored XSS against a developer who opens an attacker-written file such as var/log/dev.log in the profiler. This issue is fixed in versions 6.4.40, 7.4.12, and 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 <code>{$line}</code> 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.

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.4.24 until 6.4.40, 7.4.12, and 8.0.12, the development profiler file_excerpt Twig filter escapes PHP files through highlight_string() but interpolates lines from non-PHP files directly into <code> elements, allowing stored XSS against a developer who opens an attacker-written file such as var/log/dev.log in the profiler. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.4.24 until 6.4.40, 7.4.12, and 8.0.12, the development profiler file_excerpt Twig filter escapes PHP files through highlight_string() but interpolates lines from non-PHP files directly into <code> elements, allowing stored XSS against a developer who opens an attacker-written file such as var/log/dev.log in the profiler. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.4.24 until 6.4.40, 7.4.12, and 8.0.12, the development profiler file_excerpt Twig filter escapes PHP files through highlight_string() but interpolates lines from non-PHP files directly into <code> elements, allowing stored XSS against a developer who opens an attacker-written file such as var/log/dev.log in the profiler. This issue is fixed in versions 6.4.40, 7.4.12, and 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 <code>{$line}</code> 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.

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.4.24 until 6.4.40, 7.4.12, and 8.0.12, the development profiler file_excerpt Twig filter escapes PHP files through highlight_string() but interpolates lines from non-PHP files directly into <code> elements, allowing stored XSS against a developer who opens an attacker-written file such as var/log/dev.log in the profiler. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.