Silverstripe UserForms: Remote code execution via userforms email subject

{
  "id": "147c7fb8e36dc57bd50f26400ca4bdbbb417b85730531c334c6866ea684f6aaa",
  "url": "https://osv.dev/vulnerability/CVE-2026-54721",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Silverstripe UserForms: Remote code execution via userforms email subject",
    "summary": "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.",
    "evidence": "osv:CVE-2026-54721",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-54721",
      "aliases": [
        "CVE-2026-54721",
        "GHSA-g8wr-r2v2-vqc6"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/silverstripe/silverstripe-userforms",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "c55494ad7c717b199a3c1663b43a54db5d95604c"
                },
                {
                  "introduced": "982819c09734e2d58a931cab1e9d869012ddc016"
                },
                {
                  "fixed": "23c069866900c19b499bfa997d1e251e97491702"
                },
                {
                  "introduced": "4418856b97c398bfe54b4f4f93e100cc7997d06b"
                },
                {
                  "fixed": "c371b6953d2b2ee8fdf2a3a771701c583b9b8333"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "6.4.9"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "7.0.0"
                      },
                      {
                        "fixed": "7.0.7"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "introduced": "7.1.0"
                      },
                      {
                        "fixed": "7.1.1"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "23c069866900c19b499bfa997d1e251e97491702"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c55494ad7c717b199a3c1663b43a54db5d95604c"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c55494ad7c717b199a3c1663b43a54db5d95604c"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "6.4.9"
                  },
                  {
                    "range": [
                      {
                        "fixed": "23c069866900c19b499bfa997d1e251e97491702"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "7.0.7"
                  },
                  {
                    "range": [
                      {
                        "fixed": "c371b6953d2b2ee8fdf2a3a771701c583b9b8333"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "7.1.1"
                  }
                ]
              }
            }
          ],
          "versions": [
            "7.1.0-rc1",
            "7.1.0",
            "6.4.8",
            "7.0.6",
            "7.0.5",
            "7.0.4",
            "6.4.7",
            "7.0.3",
            "6.4.6",
            "7.0.2",
            "6.4.5",
            "7.0.1",
            "6.4.4",
            "6.4.3",
            "7.0.0",
            "6.4.2",
            "6.4.1",
            "6.4.0",
            "6.4.0-rc1",
            "6.4.0-beta1",
            "6.3.0-rc1",
            "6.3.0-beta1",
            "6.2.0-rc1",
            "6.2.0-beta1",
            "6.1.0-beta1",
            "6.0.0-beta1",
            "5.12.0",
            "5.11.0",
            "5.9.2",
            "5.10.0-alpha1",
            "5.9.1",
            "5.9.0-beta1",
            "5.7.0",
            "5.1.0",
            "5.0.0-beta2",
            "5.0.0-beta1",
            "4.1.0",
            "4.0.1",
            "4.0.0",
            "3.1.1",
            "3.1.0",
            "3.0.2",
            "3.0.1",
            "3.0.0",
            "3.0.0-beta1",
            "2.0.10",
            "2.0.9",
            "2.0.8",
            "2.0.7",
            "2.0.6",
            "2.0.5",
            "2.0.3",
            "2.0.2",
            "2.0.1-rc1",
            "2.0.1",
            "1.1.0-beta",
            "0.4"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-54721.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:22.160871285Z",
      "provider": "osv",
      "references": [
        "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/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54721.json",
        "https://github.com/silverstripe/silverstripe-userforms/security/advisories/GHSA-g8wr-r2v2-vqc6",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-54721",
        "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"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-94"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54721.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-54721",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 488181,
  "published_at": "2026-08-27T16:52:46.023+00:00"
}