CVE-2026-54721: Silverstripe UserForms: Remote code execution via userforms email subject
Impact The userform email subject field in the CMS is vulnerable to a specially crafted payload being used to run arbitrary code on the server.
Reported by Jack Wallace from Bastion Security
Other sources
Silverstripe UserForms provides a visual form builder for the Silverstripe CMS. From 6.0.0 until 6.4.9, 7.0.7, and 7.1.1, the userform email recipient subject field in the CMS accepts a specially crafted payload that can be interpreted as executable server-side code. An authenticated CMS user with permission to configure a UserForms email recipient can use the subject field to run arbitrary code on the server, compromising confidentiality, integrity, and availability. This issue is fixed in versions 6.4.9, 7.0.7, and 7.1.1.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
composer/silverstripe/userformsto a version that resolves this vulnerability.Fixed in 7.1.1 - Upgrade
Upgrade
composer/silverstripe/userformsto a version that resolves this vulnerability.Fixed in 7.0.7 - Upgrade
Upgrade
composer/silverstripe/userformsto a version that resolves this vulnerability.Fixed in 6.4.9 - Upgrade
Upgrade
Silverstripe UserForms (Silverstripe CMS)to a version that resolves this vulnerability.Fixed in 6.4.9 - Upgrade
Upgrade
Silverstripe UserForms (Silverstripe CMS)to a version that resolves this vulnerability.Fixed in 7.0.7 - Upgrade
Upgrade
Silverstripe UserForms (Silverstripe CMS)to a version that resolves this vulnerability.Fixed in 7.1.1
Event History
Frequently Asked Questions
What level of access does an attacker need to exploit this issue?
The CVSS vector indicates that an attacker needs low-level privileges and can exploit the issue remotely without user interaction.
What is the likely impact of successful exploitation?
A specially crafted value in a userform email subject field can cause arbitrary code to run on the server. The reported impact includes high confidentiality, integrity, and availability effects.
Is a default installation known to be affected?
The available information does not state whether the vulnerable userform email-subject behavior is enabled or reachable in a default configuration.