Symfony's HtmlSanitizer URL Attributes Pass Through BiDi Override Characters → Visual href Spoofing
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.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | symfony/html-sanitizer | >= 6.1.0, < 6.4.40, >= 7.0.0, < 7.4.12, >= 8.0.0, < 8.0.12 | 6.4.40, 7.4.12, 8.0.12 |
| Composer package | symfony/symfony | >= 6.1.0, < 6.4.40, >= 7.0.0, < 7.4.12, >= 8.0.0, < 8.0.12 | 6.4.40, 7.4.12, 8.0.12 |
References
- https://github.com/symfony/symfony/security/advisories/GHSA-h5vq-qfcg-4m6p
- https://github.com/symfony/symfony/commit/743a435e948b897ef2b5564ac438d4beb95d2526
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/html-sanitizer/CVE-2026-45064.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-45064.yaml
- https://github.com/symfony/symfony
- https://symfony.com/cve-2026-45064
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N- Weakness (CWE)
CWE-1007, CWE-451- Platform
- Composer
- Package
symfony/html-sanitizer, symfony/symfony- Disclosed
- 27.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-h5vq-qfcg-4m6p - CC BY 4.0
Vulnerability history: symfony/html-sanitizer
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 5
- First → latest
- 05.2026 06.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Medium 4
- Low 1
Disclosures per year
- 2026: 5
-
Symfony's HtmlSanitizer URL Attributes Pass Through BiDi Override Characters → Visual href Spoofing this entry
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