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.
HIGH
Vulnerability intelligence
CVE-2026-54721
CVSS 3.18.8
SeverityHigh
Known exploitedNo
NVD references:
- https://github.com/silverstripe/silverstripe-userforms/commit/23c069866900c19b499bfa997d1e251e97491702
- https://github.com/silverstripe/silverstripe-userforms/commit/c55494ad7c717b199a3c1663b43a54db5d95604c
- https://github.com/silverstripe/silverstripe-userforms/pull/1441
- https://github.com/silverstripe/silverstripe-userforms/pull/1442
- https://github.com/silverstripe/silverstripe-userforms/releases/tag/6.4.9
- https://github.com/silverstripe/silverstripe-userforms/releases/tag/7.0.7
- https://github.com/silverstripe/silverstripe-userforms/releases/tag/7.1.1
- https://github.com/silverstripe/silverstripe-userforms/security/advisories/GHSA-g8wr-r2v2-vqc6
Primary source: NIST National Vulnerability Database