CVE-2026-48760
Fix: symfony/symfony@b21a626CVE-2026-48760 is a CWE-451 vulnerability in symfony/html-sanitizer. O3 Security confirms whether CVE-2026-48760 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Symfony: HtmlSanitizer URL Parser Deny Gates Underinclusive: Percent-Encoded BiDi Marks and Unicode Whitespace Bypass Visual-Spoofing Defense
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-48760.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
symfony/html-sanitizer🐘symfony/html-sanitizer🐘symfony/html-sanitizer🐘symfony/symfony🐘symfony/symfony🐘symfony/symfonyReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 6.1.0 until 6.4.41, 7.4.13, and 8.0.13, UrlSanitizer::parse() rejected raw BiDi formatting characters but not percent-encoded forms and used an ASCII-only whitespace check, allowing sanitized URLs to retain visual-spoofing characters that downstream consumers could decode or display. This issue is fixed in versions 6.4.41, 7.4.13, and 8.0.13.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/html-sanitizer | ≥ 6.1.0&&< 6.4.41 | 6.4.41 |
| 🐘Packagist | symfony/html-sanitizer | ≥ 7.0.0&&< 7.4.13 | 7.4.13 |
| 🐘Packagist | symfony/html-sanitizer | ≥ 8.0.0&&< 8.0.13 | 8.0.13 |
| 🐘Packagist | symfony/symfony | ≥ 6.1.0&&< 6.4.41 | 6.4.41 |
| 🐘Packagist | symfony/symfony | ≥ 7.0.0&&< 7.4.13 | 7.4.13 |
| 🐘Packagist | symfony/symfony | ≥ 8.0.0&&< 8.0.13 | 8.0.13 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/html-sanitizer. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update symfony/html-sanitizer to 6.4.41 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48760 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-48760 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-48760. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-48760 in your dependencies?
O3 detects CVE-2026-48760 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.