Medium severity · published Jul 14, 2026
CVE-2026-45753
Symfony: HtmlSanitizer UrlAttributeSanitizer Omits action/formaction/poster/cite — javascript: URI Survives Sanitization (XSS)
6.1
CVSS
0.3%
EPSS
No
On KEV
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, UrlAttributeSanitizer::getSupportedAttributes() omits URL-valued attributes including action, formaction, poster, and cite, so configurations that admit those attributes can leave javascript: URIs unsanitized and enable XSS when the resulting HTML is rendered or a victim submits a form or clicks a button. This issue is fixed in versions 6.4.40, 7.4.12, and 8.0.12.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 27% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HT
html-sanitizer · symfony
>= 6.1.0-BETA1, < 6.4.40; >= 7.0.0-BETA1, < 7.4.12; >= 8.0.0-BETA1, < 8.0.12 · source: vendor
SY
symfony · symfony
>= 6.1.0-BETA1, < 6.4.40; >= 7.0.0-BETA1, < 7.4.12; >= 8.0.0-BETA1, < 8.0.12 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-45753
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-45753
Patch
https://github.com/symfony/symfony/commit/487728e7e180a674a6d4c01bd0cb56161cc441b7
Product
https://github.com/symfony/symfony/releases/tag/v6.4.40
Product
https://github.com/symfony/symfony/releases/tag/v7.4.12
Product
https://github.com/symfony/symfony/releases/tag/v8.0.12
Patch
https://github.com/symfony/symfony/security/advisories/GHSA-hhg7-c65m-h7ff
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