Meta Refresh URL Redirection Vulnerability in Symfony by SensioLabs
CVE-2026-121373

5.3MEDIUM

Key Information:

Vendor

Sensiolabs

Status
Symfony
Vendor
CVE Published:
4 November 2026

What is CVE-2026-121373?

The Symfony HtmlSanitizer component's MetaRefreshAttributeSanitizer has a flaw that permits circumvention of its sanitization process through a narrow regular expression. This can enable attackers to redirect users to untrusted sites by leveraging the refresh URL in meta tags. A configuration allowing meta tags with http-equiv and content attributes can expose this vulnerability. To mitigate this risk, affected users must upgrade to the latest versions of Symfony.

Affected Version(s)

symfony 6.1 < 6.4.50

symfony 7 < 7.4.23

symfony 8 < 8.1.11

References

https://github.com/symfony/symfony/security/advisories/GH...
third-party-advisory
https://github.com/symfony/symfony/commit/2d4c4fe36200858...
patch

CVSS V4

Score:
5.3
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
Unknown

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Ilia Alshanetsky
Nicolas Grekas
.