CVE-2026-107848

Contao: Cross-site request forgery in custom backend actions

RequestTokenListener is the only generic REQUEST_TOKEN validator in Contao and it only runs on POST. On the GET side the guard is local and declarative, and it only fires when an act parameter is present. Every back end action dispatched through a different parameter therefore has no CSRF protection at all. This is a family rather than a single bug.

An attacker who gets a logged in back end user to load a URL performs back end actions as that user, with no token and no confirmation. Because the exposure follows from the dispatch mechanism rather than from one callback, every present and future key= action inherits it.

Honest bound. The victim must be authenticated in the back end and must load the URL, and the reachable actions are limited to the modules that user can access. We have not found a key= action that grants privileges; the ones we verified are destructive or state changing rather than escalating.

A victim's authenticated browser session is used to submit forged requests to an application that cannot distinguish them from legitimate ones. Typical impact: state-changing actions performed as the victim without their consent.

CVE-2026-107848 has a CVSS score of 3.5 (Low). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.3.50, 5.7.12); upgrading removes the vulnerable code path.

Kodem intelligence

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1. What is CVE-2026-107848? CVE-2026-107848 is a low-severity cross-site request forgery (CSRF) vulnerability in contao/core-bundle (composer), affecting versions >= 4.0.0, < 5.3.50. It is fixed in 5.3.50, 5.7.12. A victim's authenticated browser session is used to submit forged requests to an application that cannot distinguish them from legitimate ones.
2. How severe is CVE-2026-107848? CVE-2026-107848 has a CVSS score of 3.5 (Low). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of contao/core-bundle are affected by CVE-2026-107848? contao/core-bundle (composer) versions >= 4.0.0, < 5.3.50 is affected.
4. Is there a fix for CVE-2026-107848? Yes. CVE-2026-107848 is fixed in 5.3.50, 5.7.12. Upgrade to this version or later.
5. Is CVE-2026-107848 exploitable, and should I be worried? Whether CVE-2026-107848 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-107848 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-107848?
   • Upgrade contao/core-bundle to 5.3.50 or later
   • Upgrade contao/core-bundle to 5.7.12 or later

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