Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.1.0-BETA1 until 6.4.40, 7.4.12, and 8.0.12, UrlSanitizer::parse() passes Unicode explicit-direction BiDi formatting characters through into sanitized href and src attributes, allowing sanitized content to display a link destination that visually differs from the actual destination and enabling phishing-style visual spoofing. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.
Affected: Packagist: symfony/html-sanitizer, Packagist: symfony/symfony
### Description
`Symfony\Component\HtmlSanitizer\TextSanitizer\UrlSanitizer::parse()` (used by `UrlSanitizer::sanitize()` and therefore by every `HtmlSanitizer` config that allows links or media) accepts URLs that contain Unicode explicit-direction BiDi formatting characters: U+202A–U+202E (LRE / RLE / PDF / LRO / RLO) and U+2066–U+2069 (LRI / RLI / FSI / PDI). These characters are passed through unchanged into the `href` / `src` attributes produced by `HtmlSanitizer`. When the resulting HTML is rendered in a browser, the override characters reverse or alter the visual ordering of the URL text, so the displayed link can differ arbitrarily from the actual destination: a classic visual-spoofing / phishing primitive against viewers of sanitized content.
### Resolution
`UrlSanitizer::parse()` now rejects URLs containing the explicit-direction BiDi formatting code points (U+202A–U+202E, U+2066–U+2069) before invoking the underlying URL parser. As an unrelated companion fix in the same patch, spaces inside path/query/fragment are now percent-encoded rather than rejected outright, while spaces in the scheme/authority remain rejected by the post-encoding whitespace check.
The patch for this issue is available [here](https://github.com/symfony/symfony/commit/743a435e948b897ef2b5564ac438d4beb95d2526) for branch 5.4.
### Credits
Symfony would like to thank Himanshu Anand for reporting the issue and Nicolas Grekas for providing the fix.
Affected: Ubuntu:16.04:LTS: symfony, Ubuntu:Pro:18.04:LTS: symfony, Ubuntu:Pro:20.04:LTS: symfony, Ubuntu:Pro:22.04:LTS: symfony, Ubuntu:Pro:24.04:LTS: symfony, Ubuntu:25.10: symfony, Ubuntu:26.04:LTS: symfony
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.1.0-BETA1 until 6.4.40, 7.4.12, and 8.0.12, UrlSanitizer::parse() passes Unicode explicit-direction BiDi formatting characters through into sanitized href and src attributes, allowing sanitized content to display a link destination that visually differs from the actual destination and enabling phishing-style visual spoofing. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.