Craft CMS up to 4.16.17/5.8.21 src/services/Fields.php assembleLayoutFromPost externally-controlled input to select classes or code

Summaryinfo

A vulnerability has been found in Craft CMS up to 4.16.17/5.8.21 and classified as problematic. The impacted element is the function assembleLayoutFromPost of the file src/services/Fields.php. Performing a manipulation results in use of externally-controlled input to select classes or code. This vulnerability was named CVE-2026-25498. The attack may be initiated remotely. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic has been found in Craft CMS up to 4.16.17/5.8.21. This affects the function assembleLayoutFromPost of the file src/services/Fields.php. The manipulation with an unknown input leads to a use of externally-controlled input to select classes or code vulnerability. CWE is classifying the issue as CWE-470. The product uses external input with reflection to select which classes or code to use, but it does not sufficiently prevent the input from selecting improper classes or code. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Craft is a platform for creating digital experiences. In versions 4.0.0-RC1 through 4.16.17 and 5.0.0-RC1 through 5.8.21, a Remote Code Execution (RCE) vulnerability exists in Craft CMS where the assembleLayoutFromPost() function in src/services/Fields.php fails to sanitize user-supplied configuration data before passing it to Craft::createObject(). This allows authenticated administrators to inject malicious Yii2 behavior configurations that execute arbitrary system commands on the server. This vulnerability represents an unpatched variant of the behavior injection vulnerability addressed in CVE-2025-68455, affecting different endpoints through a separate code path. This vulnerability is fixed in 5.8.22.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-25498 since 02/02/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Additional levels of successful authentication are necessary for exploitation. Technical details are known, but no exploit is available.

By approaching the search of inurl:src/services/Fields.php it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 4.16.18 or 5.8.22 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 395c64f0b80b507be1c862a2ec942eaacb353748 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Content Management System

Vendor

• Craft

Name

• CMS

Version

• 4.16.0
• 4.16.1
• 4.16.2
• 4.16.3
• 4.16.4
• 4.16.5
• 4.16.6
• 4.16.7
• 4.16.8
• 4.16.9
• 4.16.10
• 4.16.11
• 4.16.12
• 4.16.13
• 4.16.14
• 4.16.15
• 4.16.16
• 4.16.17
• 5.8.0
• 5.8.1
• 5.8.2
• 5.8.3
• 5.8.4
• 5.8.5
• 5.8.6
• 5.8.7
• 5.8.8
• 5.8.9
• 5.8.10
• 5.8.11
• 5.8.12
• 5.8.13
• 5.8.14
• 5.8.15
• 5.8.16
• 5.8.17
• 5.8.18
• 5.8.19
• 5.8.20
• 5.8.21

License

• free

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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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