What’s Vulnerable › Vulnerabilities

CVE-2026-45066: Symfony: HtmlSanitizer allowLinkHosts() / allowMediaHosts() Bypass via URL-Parser Differentials and <area> Misclassification

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-14 · updated 2026-07-16
• Weakness: CWE-184

Description

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, HtmlSanitizer URL sanitization can allow off-allowlist URLs through allowLinkHosts() or allowMediaHosts() because UrlSanitizer::parse() follows RFC 3986 while browsers follow WHATWG URL parsing, and because <area href> is checked against the media policy rather than the link policy. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.

Affected products

• symfony: from 6.1.0 before 6.4.40; from 7.0.0 before 7.4.12; from 8.0.0 before 8.0.12 — fixed in 6.4.40, 7.4.12, 8.0.12

How to fix

Upgrade to a fixed version: symfony 6.4.40, 7.4.12, 8.0.12. Check the vendor advisory for mitigations.

References

• https://github.com/symfony/symfony/commit/d506b556d3d3906f3e8660ad82257ce87edbaac4
• https://github.com/symfony/symfony/releases/tag/v6.4.40
• https://github.com/symfony/symfony/releases/tag/v7.4.12
• https://github.com/symfony/symfony/releases/tag/v8.0.12
• https://github.com/symfony/symfony/security/advisories/GHSA-qc95-4862-92fh

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