Description
Contao is an Open Source CMS. From version 4.0.0 until 5.3.50 and 5.7.12, an unauthenticated visitor can submit a comment whose email or website metadata is rendered without sufficient attribute and URL encoding by listComments() in comments-bundle/contao/dca/tl_comments.php. When a backend user opens the Comments module, attacker-controlled script can execute in the Contao backend origin under that user's session. Unpublished comments remain visible to moderators, so moderation does not prevent exposure. This issue is fixed in versions 5.3.50 and 5.7.12.
Published: 2026-10-09
Score: 9.3 Critical
EPSS: n/a
KEV: No
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-628f-v4f6-p37r Contao: Cross-site scripting in the comments bundle
History

Fri, 09 Oct 2026 20:45:00 +0000

Type Values Removed Values Added
First Time appeared Contao
Contao contao
Vendors & Products Contao
Contao contao

Fri, 09 Oct 2026 19:45:00 +0000

Type Values Removed Values Added
Description Contao is an Open Source CMS. From version 4.0.0 until 5.3.50 and 5.7.12, an unauthenticated visitor can submit a comment whose email or website metadata is rendered without sufficient attribute and URL encoding by listComments() in comments-bundle/contao/dca/tl_comments.php. When a backend user opens the Comments module, attacker-controlled script can execute in the Contao backend origin under that user's session. Unpublished comments remain visible to moderators, so moderation does not prevent exposure. This issue is fixed in versions 5.3.50 and 5.7.12.
Title Contao: Cross-site scripting in the comments bundle
Weaknesses CWE-116
CWE-79
References
Metrics cvssV3_1

{'score': 9.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-09T19:51:45.890Z

Reserved: 2026-10-08T22:34:49.291Z

Link: CVE-2026-107845

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-09T20:17:10.457

Modified: 2026-10-09T20:17:10.457

Link: CVE-2026-107845

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-09T20:30:11Z

Weaknesses
  • CWE-116

    Improper Encoding or Escaping of Output

  • CWE-79

    Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')