CVE-2026-48761: Symfony: HtmlSanitizer UrlAttributeSanitizer Misses URL Attributes on <object>, <applet>, <iframe>, <img> and the URL Inside <meta http-equiv="refresh"> content

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 2026-07-21
Weakness: CWE-79

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, UrlAttributeSanitizer::getSupportedAttributes() omitted URL-bearing attributes on <object>, <applet>, <iframe>, and <img>, and <meta http-equiv="refresh"> URLs inside content bypassed URL sanitization, allowing explicitly enabled elements or attributes to pass javascript: and similar payloads into sanitized output. This issue is fixed in versions 6.4.41, 7.4.13, and 8.0.13.

Affected products

symfony: from 6.1.0 before 6.4.41; from 7.0.0 before 7.4.13; from 8.0.0 before 8.0.13 — fixed in 6.4.41, 7.4.13, 8.0.13

How to fix

Upgrade to a fixed version: symfony 6.4.41, 7.4.13, 8.0.13. Check the vendor advisory for mitigations.

References

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