CVE-2026-54721

Silverstripe UserForms: Remote code execution via userforms email subject

HIGH
8.8
CVSS Score
Published: August 27, 2026 at 04:52 PM UTC
Updated: September 9, 2026 at 09:27 PM UTC
1 product affected across 1 vendorUserForms

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Severity
HIGH8.8
Exploit prediction
EPSS 0.7%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 6.4.9v < 7.0.7v < 7.1.1
Affected range stops below 6.4.9, so it looks safe — our inference, not a vendor statement
Affected range stops below 7.0.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 7.1.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.8HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-94

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