CVE-2026-107848: Contao: Cross-site request forgery in custom backend actions

CVE-2026-107848 · Severity: low · CVSS 3.5 · Published 2026-10-09

Contao is an Open Source CMS. From version 4.0.0 until 5.3.50 and 5.7.12, RequestTokenListener validates REQUEST_TOKEN only for POST requests, while the declarative GET guard runs only when an act parameter is present. Backend actions dispatched through the key parameter can therefore execute without a CSRF token when an authenticated backend user loads an attacker-controlled URL. Reachable actions remain limited to modules available to that user, and the advisory demonstrates destructive or state-changing actions rather than privilege escalation. This issue is fixed in versions 5.3.50 and 5.7.12.

Technologies: contao/core-bundle (Packagist). Vendors: Packagist.

Quick answers

Is CVE-2026-107848 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-107848 being exploited in the wild.
How severe is CVE-2026-107848?
Low severity, with a CVSS score of 3.5, published 9 October 2026.
Which products and versions are affected?
contao/core-bundle (Packagist) ECOSYSTEM:introduced=4.0.0,fixed=5.3.50.
Is there a fix for CVE-2026-107848?
Yes. contao/core-bundle (Packagist): upgrade to 5.3.50 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-107848?
Check whether you run contao/core-bundle (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • contao/core-bundle (Packagist): upgrade to 5.3.50 or later
    composer require contao/core-bundle:^5.3.50

Affected products

  • contao/core-bundle (Packagist) ECOSYSTEM:introduced=4.0.0,fixed=5.3.50

Identifiers

  • CVE-2026-107848
  • GHSA-9ff2-p842-45wq

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