Symfony: HtmlSanitizer UrlAttributeSanitizer Misses URL Attributes
The advisory, in context
Description
Symfony\Component\HtmlSanitizer\Visitor\AttributeSanitizer\UrlAttributeSanitizer::getSupportedAttributes() enumerates the attribute names whose values are scrubbed through UrlSanitizer::sanitize() (scheme and host allow-lists, javascript: rejection, BiDi check, etc.). The list is ['src', 'href', 'lowsrc', 'background', 'ping', 'action', 'formaction', 'poster', 'cite']. Other URL-bearing attributes are absent: <object data=…>, <applet codebase=…>, <applet archive=…> and <object archive=…>, <iframe longdesc=…> and <img longdesc=…>. When an integrator opts these elements/attributes in via allowElement('object', ['data']), allowElement('applet', ['codebase']), etc., or via allowAttribute(), no URL sanitization runs: data="javascript:alert(1)" and similar payloads ship through unchanged into the output, enabling stored XSS.
<meta http-equiv="refresh" content="0; url=…"> is the same class of bug routed differently: the URL is embedded inside a multi-field content attribute that the per-attribute sanitizer cannot detect from the attribute name alone. Integrators who enable <meta> with the content attribute (e.g. via allowStaticElements()) see content="0; url=javascript:alert(1)" pass through, producing a refresh-driven navigation to a javascript: URL.
Default configurations are not affected: <object>, <applet> and <iframe> are not in W3CReference::BODY_ELEMENTS and <meta> requires an explicit opt-in to <head> context. The vulnerability surface is integrators who explicitly allow any of those elements together with the listed URL-bearing attributes.
Resolution
UrlAttributeSanitizer now also routes data, codebase, archive and longdesc through UrlSanitizer::sanitize(). A new MetaRefreshAttributeSanitizer registered as a default attribute sanitizer detects the <delay>; url=<url> syntax inside <meta content>, sanitizes the embedded URL, and drops the attribute if the URL is rejected; non-refresh meta content values are passed through unchanged.
The patches for this issue are available here for branch 6.4 (and forward-ported to 7.4, 8.0 and 8.1).
Credits
Symfony would like to thank Scott Arciszewski (Trail of Bits) for reporting the issue and Nicolas Grekas for providing the fix.
Affected packages
Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.
From 6.1.0 before 6.4.41
Fixed in 6.4.41
33 explicitly affected versions
v6.1.0, v6.1.11, v6.1.9, v6.2.0, v6.2.0-BETA1, v6.2.0-RC1, v6.2.2, v6.2.5, v6.2.7, v6.3.0, v6.3.0-BETA1, v6.3.0-RC1, v6.3.12, v6.3.4, v6.3.7, v6.4.0, v6.4.0-BETA1, v6.4.0-BETA2, v6.4.0-RC1, v6.4.12, v6.4.13, v6.4.17, v6.4.18, v6.4.21, v6.4.24, v6.4.25, v6.4.28, v6.4.3, v6.4.35, v6.4.4, v6.4.40, v6.4.7, v6.4.8
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "6.1.0"
},
{
"fixed": "6.4.41"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v6.1.0",
"v6.1.11",
"v6.1.9",
"v6.2.0",
"v6.2.0-BETA1",
"v6.2.0-RC1",
"v6.2.2",
"v6.2.5",
"v6.2.7",
"v6.3.0",
"v6.3.0-BETA1",
"v6.3.0-RC1",
"v6.3.12",
"v6.3.4",
"v6.3.7",
"v6.4.0",
"v6.4.0-BETA1",
"v6.4.0-BETA2",
"v6.4.0-RC1",
"v6.4.12",
"v6.4.13",
"v6.4.17",
"v6.4.18",
"v6.4.21",
"v6.4.24",
"v6.4.25",
"v6.4.28",
"v6.4.3",
"v6.4.35",
"v6.4.4",
"v6.4.40",
"v6.4.7",
"v6.4.8"
]
}From 7.0.0 before 7.4.13
Fixed in 7.4.13
33 explicitly affected versions
v7.0.0, v7.0.3, v7.0.4, v7.0.7, v7.0.8, v7.1.0, v7.1.0-BETA1, v7.1.0-RC1, v7.1.1, v7.1.10, v7.1.11, v7.1.5, v7.1.6, v7.2.0, v7.2.0-BETA1, v7.2.0-RC1, v7.2.2, v7.2.3, v7.2.6, v7.2.9, v7.3.0, v7.3.0-BETA1, v7.3.0-RC1, v7.3.2, v7.3.3, v7.3.6, v7.4.0, v7.4.0-BETA1, v7.4.0-BETA2, v7.4.0-RC1, v7.4.12, v7.4.7, v7.4.8
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "7.0.0"
},
{
"fixed": "7.4.13"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v7.0.0",
"v7.0.3",
"v7.0.4",
"v7.0.7",
"v7.0.8",
"v7.1.0",
"v7.1.0-BETA1",
"v7.1.0-RC1",
"v7.1.1",
"v7.1.10",
"v7.1.11",
"v7.1.5",
"v7.1.6",
"v7.2.0",
"v7.2.0-BETA1",
"v7.2.0-RC1",
"v7.2.2",
"v7.2.3",
"v7.2.6",
"v7.2.9",
"v7.3.0",
"v7.3.0-BETA1",
"v7.3.0-RC1",
"v7.3.2",
"v7.3.3",
"v7.3.6",
"v7.4.0",
"v7.4.0-BETA1",
"v7.4.0-BETA2",
"v7.4.0-RC1",
"v7.4.12",
"v7.4.7",
"v7.4.8"
]
}From 8.0.0 before 8.0.13
Fixed in 8.0.13
4 explicitly affected versions
v8.0.0, v8.0.12, v8.0.7, v8.0.8
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "8.0.0"
},
{
"fixed": "8.0.13"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v8.0.0",
"v8.0.12",
"v8.0.7",
"v8.0.8"
]
}From 6.1.0 before 6.4.41
Fixed in 6.4.41
97 explicitly affected versions
v6.1.0, v6.1.1, v6.1.10, v6.1.11, v6.1.12, v6.1.2, v6.1.3, v6.1.4, v6.1.5, v6.1.6, v6.1.7, v6.1.8, v6.1.9, v6.2.0, v6.2.0-BETA1, v6.2.0-BETA2, v6.2.0-BETA3, v6.2.0-RC1, v6.2.0-RC2, v6.2.1, v6.2.10, v6.2.11, v6.2.12, v6.2.13, v6.2.14, v6.2.2, v6.2.3, v6.2.4, v6.2.5, v6.2.6, v6.2.7, v6.2.8, v6.2.9, v6.3.0, v6.3.0-BETA1, v6.3.0-BETA2, v6.3.0-BETA3, v6.3.0-RC1, v6.3.0-RC2, v6.3.1, v6.3.10, v6.3.11, v6.3.12, v6.3.2, v6.3.3, v6.3.4, v6.3.5, v6.3.6, v6.3.7, v6.3.8, v6.3.9, v6.4.0, v6.4.0-BETA1, v6.4.0-BETA2, v6.4.0-BETA3, v6.4.0-RC1, v6.4.0-RC2, v6.4.1, v6.4.10, v6.4.11, v6.4.12, v6.4.13, v6.4.14, v6.4.15, v6.4.16, v6.4.17, v6.4.18, v6.4.19, v6.4.2, v6.4.20, v6.4.21, v6.4.22, v6.4.23, v6.4.24, v6.4.25, v6.4.26, v6.4.27, v6.4.28, v6.4.29, v6.4.3, v6.4.30, v6.4.31, v6.4.32, v6.4.33, v6.4.34, v6.4.35, v6.4.36, v6.4.37, v6.4.38, v6.4.39, v6.4.4, v6.4.40, v6.4.5, v6.4.6, v6.4.7, v6.4.8, v6.4.9
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "6.1.0"
},
{
"fixed": "6.4.41"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v6.1.0",
"v6.1.1",
"v6.1.10",
"v6.1.11",
"v6.1.12",
"v6.1.2",
"v6.1.3",
"v6.1.4",
"v6.1.5",
"v6.1.6",
"v6.1.7",
"v6.1.8",
"v6.1.9",
"v6.2.0",
"v6.2.0-BETA1",
"v6.2.0-BETA2",
"v6.2.0-BETA3",
"v6.2.0-RC1",
"v6.2.0-RC2",
"v6.2.1",
"v6.2.10",
"v6.2.11",
"v6.2.12",
"v6.2.13",
"v6.2.14",
"v6.2.2",
"v6.2.3",
"v6.2.4",
"v6.2.5",
"v6.2.6",
"v6.2.7",
"v6.2.8",
"v6.2.9",
"v6.3.0",
"v6.3.0-BETA1",
"v6.3.0-BETA2",
"v6.3.0-BETA3",
"v6.3.0-RC1",
"v6.3.0-RC2",
"v6.3.1",
"v6.3.10",
"v6.3.11",
"v6.3.12",
"v6.3.2",
"v6.3.3",
"v6.3.4",
"v6.3.5",
"v6.3.6",
"v6.3.7",
"v6.3.8",
"v6.3.9",
"v6.4.0",
"v6.4.0-BETA1",
"v6.4.0-BETA2",
"v6.4.0-BETA3",
"v6.4.0-RC1",
"v6.4.0-RC2",
"v6.4.1",
"v6.4.10",
"v6.4.11",
"v6.4.12",
"v6.4.13",
"v6.4.14",
"v6.4.15",
"v6.4.16",
"v6.4.17",
"v6.4.18",
"v6.4.19",
"v6.4.2",
"v6.4.20",
"v6.4.21",
"v6.4.22",
"v6.4.23",
"v6.4.24",
"v6.4.25",
"v6.4.26",
"v6.4.27",
"v6.4.28",
"v6.4.29",
"v6.4.3",
"v6.4.30",
"v6.4.31",
"v6.4.32",
"v6.4.33",
"v6.4.34",
"v6.4.35",
"v6.4.36",
"v6.4.37",
"v6.4.38",
"v6.4.39",
"v6.4.4",
"v6.4.40",
"v6.4.5",
"v6.4.6",
"v6.4.7",
"v6.4.8",
"v6.4.9"
]
}From 7.0.0 before 7.4.13
Fixed in 7.4.13
71 explicitly affected versions
v7.0.0, v7.0.1, v7.0.10, v7.0.2, v7.0.3, v7.0.4, v7.0.5, v7.0.6, v7.0.7, v7.0.8, v7.0.9, v7.1.0, v7.1.0-BETA1, v7.1.0-RC1, v7.1.1, v7.1.10, v7.1.11, v7.1.2, v7.1.3, v7.1.4, v7.1.5, v7.1.6, v7.1.7, v7.1.8, v7.1.9, v7.2.0, v7.2.0-BETA1, v7.2.0-BETA2, v7.2.0-RC1, v7.2.1, v7.2.2, v7.2.3, v7.2.4, v7.2.5, v7.2.6, v7.2.7, v7.2.8, v7.2.9, v7.3.0, v7.3.0-BETA1, v7.3.0-BETA2, v7.3.0-RC1, v7.3.1, v7.3.10, v7.3.11, v7.3.2, v7.3.3, v7.3.4, v7.3.5, v7.3.6, v7.3.7, v7.3.8, v7.3.9, v7.4.0, v7.4.0-BETA1, v7.4.0-BETA2, v7.4.0-RC1, v7.4.0-RC2, v7.4.0-RC3, v7.4.1, v7.4.10, v7.4.11, v7.4.12, v7.4.2, v7.4.3, v7.4.4, v7.4.5, v7.4.6, v7.4.7, v7.4.8, v7.4.9
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "7.0.0"
},
{
"fixed": "7.4.13"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v7.0.0",
"v7.0.1",
"v7.0.10",
"v7.0.2",
"v7.0.3",
"v7.0.4",
"v7.0.5",
"v7.0.6",
"v7.0.7",
"v7.0.8",
"v7.0.9",
"v7.1.0",
"v7.1.0-BETA1",
"v7.1.0-RC1",
"v7.1.1",
"v7.1.10",
"v7.1.11",
"v7.1.2",
"v7.1.3",
"v7.1.4",
"v7.1.5",
"v7.1.6",
"v7.1.7",
"v7.1.8",
"v7.1.9",
"v7.2.0",
"v7.2.0-BETA1",
"v7.2.0-BETA2",
"v7.2.0-RC1",
"v7.2.1",
"v7.2.2",
"v7.2.3",
"v7.2.4",
"v7.2.5",
"v7.2.6",
"v7.2.7",
"v7.2.8",
"v7.2.9",
"v7.3.0",
"v7.3.0-BETA1",
"v7.3.0-BETA2",
"v7.3.0-RC1",
"v7.3.1",
"v7.3.10",
"v7.3.11",
"v7.3.2",
"v7.3.3",
"v7.3.4",
"v7.3.5",
"v7.3.6",
"v7.3.7",
"v7.3.8",
"v7.3.9",
"v7.4.0",
"v7.4.0-BETA1",
"v7.4.0-BETA2",
"v7.4.0-RC1",
"v7.4.0-RC2",
"v7.4.0-RC3",
"v7.4.1",
"v7.4.10",
"v7.4.11",
"v7.4.12",
"v7.4.2",
"v7.4.3",
"v7.4.4",
"v7.4.5",
"v7.4.6",
"v7.4.7",
"v7.4.8",
"v7.4.9"
]
}From 8.0.0 before 8.0.13
Fixed in 8.0.13
13 explicitly affected versions
v8.0.0, v8.0.1, v8.0.10, v8.0.11, v8.0.12, v8.0.2, v8.0.3, v8.0.4, v8.0.5, v8.0.6, v8.0.7, v8.0.8, v8.0.9
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "8.0.0"
},
{
"fixed": "8.0.13"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v8.0.0",
"v8.0.1",
"v8.0.10",
"v8.0.11",
"v8.0.12",
"v8.0.2",
"v8.0.3",
"v8.0.4",
"v8.0.5",
"v8.0.6",
"v8.0.7",
"v8.0.8",
"v8.0.9"
]
}References
- https://github.com/symfony/symfony/security/advisories/GHSA-x5qj-865h-mgvm
- https://github.com/symfony/symfony/commit/069a70f9f26e61e9de3b7f9a864a86ed24b36bd0
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/html-sanitizer/CVE-2026-48761.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-48761.yaml
- https://github.com/symfony/symfony
- https://symfony.com/cve-2026-48761