Symfony UX allows unsanitized HTML attribute injection via ComponentAttributes
Date: 2025-05
Affected: composer/symfony/ux-live-component, composer/symfony/ux-twig-component
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2025-47946
CWE: CWE-79
CVSS: 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)

### Impact Rendering `{{ attributes }}` or using any method that returns a `ComponentAttributes` instance (e.g. `only()`, `defaults()`, `without()`) ouputs attribute values directly without escaping. If these values are unsafe (e.g. contain user input), this can lead to HTML attribute injection and XSS vulnerabilities. ### Patches The issue is fixed in version `2.25.1` of `symfony/ux-twig-component` by using Twig's `EscaperRuntime` to properly escape HTML attributes in `ComponentAttributes`. If you use `symfony/ux-live-component`, you must also update it to `2.25.1` to benefit from the fix, as it reuses the `ComponentAttributes` class internally. ### Workarounds Until you can upgrade, avoid rendering `{{ attributes }}` or derived objects directly if it may contain untrusted values. Instead, use `{{ attributes.render('name') }}` for safe output of individual attributes. ### References GitHub repository: [symfony/ux](https://github.com/symfony/ux)


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Architectural layers (MAESTRO):