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CVE-2026-54721: silverstripe/userforms vulnerable to remote code execution via userforms email subject

August 27, 2026

The userform email subject field in the CMS is vulnerable to a specially crafted payload being used to run arbitrary code on the server.

References

  • github.com/FriendsOfPHP/security-advisories/blob/master/silverstripe/userforms/CVE-2026-54721.yaml
  • github.com/advisories/GHSA-g8wr-r2v2-vqc6
  • github.com/silverstripe/silverstripe-userforms/commit/23c069866900c19b499bfa997d1e251e97491702
  • github.com/silverstripe/silverstripe-userforms/commit/c55494ad7c717b199a3c1663b43a54db5d95604c
  • github.com/silverstripe/silverstripe-userforms/pull/1441
  • github.com/silverstripe/silverstripe-userforms/pull/1442
  • github.com/silverstripe/silverstripe-userforms/releases/tag/6.4.9
  • github.com/silverstripe/silverstripe-userforms/releases/tag/7.0.7
  • github.com/silverstripe/silverstripe-userforms/releases/tag/7.1.1
  • github.com/silverstripe/silverstripe-userforms/security/advisories/GHSA-g8wr-r2v2-vqc6
  • nvd.nist.gov/vuln/detail/CVE-2026-54721
  • www.silverstripe.org/download/security-releases/cve-2026-54721

Code Behaviors & Features

Detect and mitigate CVE-2026-54721 with GitLab Dependency Scanning

Secure your software supply chain by verifying that all open source dependencies used in your projects contain no disclosed vulnerabilities. Dependency Scanning using SBOM also detects vulnerabilities from proprietary advisories that this site does not include. Learn more about Dependency Scanning using SBOM →

Affected versions

All versions before 6.4.9, all versions starting from 7.0.0 before 7.0.7, all versions starting from 7.1.0 before 7.1.1

Fixed versions

  • 6.4.9
  • 7.0.7
  • 7.1.1

Solution

Upgrade to versions 6.4.9, 7.0.7, 7.1.1 or above.

Impact 8.8 HIGH

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Learn more about CVSS

Weakness

  • CWE-20: Improper Input Validation
  • CWE-94: Improper Control of Generation of Code ('Code Injection')

Source file

packagist/silverstripe/userforms/CVE-2026-54721.yml

Spotted a mistake? Edit the file on GitLab.

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