GHSA-h5vq-qfcg-4m6p Symfony's HtmlSanitizer URL Attributes Pass Through BiDi Override Characters → Visual href Spoofing

• Packagist symfony/html-sanitizer: >= 6.1.0, < 6.4.40 → fixed in 6.4.40 • Packagist symfony/html-sanitizer: >= 7.0.0, < 7.4.12 → fixed in 7.4.12 • Packagist symfony/html-sanitizer: >= 8.0.0, < 8.0.12 → fixed in 8.0.12 • Packagist symfony/symfony: >= 6.1.0, < 6.4.40 → fixed in 6.4.40 • Packagist symfony/symfony: >= 7.0.0, < 7.4.12 → fixed in 7.4.12 • Packagist symfony/symfony: >= 8.0.0, < 8.0.12 → fixed in 8.0.12

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 for branch 5.4. Credits Symfony would like to thank Himanshu Anand for reporting the issue and Nicolas Grekas for providing the fix.