Craft CMS up to 4.17.3/5.9.8 getElementIds code injection

Summaryinfo

A vulnerability, which was classified as critical, has been found in Craft CMS up to 4.17.3/5.9.8. This impacts the function BaseElementSelectConditionRule::getElementIds. This manipulation causes code injection. This vulnerability is handled as CVE-2026-31857. The attack can be initiated remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Craft CMS up to 4.17.3/5.9.8 and classified as critical. Affected by this vulnerability is the function BaseElementSelectConditionRule::getElementIds. The manipulation with an unknown input leads to a code injection vulnerability. The CWE definition for the vulnerability is CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Craft is a content management system (CMS). Prior to 5.9.9 and 4.17.4, a Remote Code Execution vulnerability exists in the Craft CMS 5 conditions system. The BaseElementSelectConditionRule::getElementIds() method passes user-controlled string input through renderObjectTemplate() -- an unsandboxed Twig rendering function with escaping disabled. Any authenticated Control Panel user (including non-admin roles such as Author or Editor) can achieve full RCE by sending a crafted condition rule via standard element listing endpoints. This vulnerability requires no admin privileges, no special permissions beyond basic control panel access, and bypasses all production hardening settings (allowAdminChanges: false, devMode: false, enableTwigSandbox: true). Users should update to the patched 5.9.9 or 4.17.4 release to mitigate the issue.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-31857 since 03/09/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059 according to MITRE ATT&CK.

Upgrading to version 4.17.4 or 5.9.9 eliminates this vulnerability. Applying the patch 8d4903647dcfd31b8d40ed027e27082013347a80 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.

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Productinfo

Type

• Content Management System

Vendor

• Craft

Name

• CMS

Version

• 4.17.0
• 4.17.1
• 4.17.2
• 4.17.3
• 5.9.0
• 5.9.1
• 5.9.2
• 5.9.3
• 5.9.4
• 5.9.5
• 5.9.6
• 5.9.7
• 5.9.8

License

• free

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