CVE-2026-54721 Silverstripe UserForms: Remote code execution via userforms email subject
Authenticated CMS users can execute arbitrary server-side code via the email subject field in Silverstripe UserForms.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54721?
CVE-2026-54721 is a high-severity code injection vulnerability in silverstripe-userforms, published on 27 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-94
Which versions are affected by CVE-2026-54721?
6 open source packages ship an affected version, including silverstripe/userforms.
| Package | Affected | Fixed in |
|---|---|---|
silverstripe/userforms Packagist | All versions | 6.4.9 |
silverstripe/userforms Packagist | All versions | 6.4.9 |
silverstripe/userforms Packagist | From 7.0.0 | 7.0.7 |
silverstripe/userforms Packagist | From 7.0.0 | 7.0.7 |
silverstripe/userforms Packagist | From 7.1.0 | 7.1.1 |
silverstripe/userforms Packagist | From 7.1.0 | 7.1.1 |
How do I fix CVE-2026-54721?
Upgrade silverstripe/userforms to a fixed version for your release line: 6.4.9, 7.0.7 or 7.1.1.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-54721 being exploited?
There is no known exploitation of CVE-2026-54721 in the wild and no public exploit code.
Sources
Also known as GHSA-g8wr-r2v2-vqc6.