Grav: Anonymous Page Content Overwrite via Form File Upload filename Override

{
  "id": "52cdbb56da2979611459f3fb54ddfae832ab44ec9618e03605a9376bf1e7ddde",
  "url": "https://osv.dev/vulnerability/CVE-2026-42845",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Grav: Anonymous Page Content Overwrite via Form File Upload filename Override",
    "summary": "The form plugin for Grav adds the ability to create and use forms. Prior to 9.1.0 , there is an unauthenticated page-content overwrite via file upload (GHSA-w4rc-p66m-x6qq). Public form uploads now strip path components from the POST-supplied filename and hard-block page-content extensions (`md`, `yaml`, `yml`, `json`, `twig`, `ini`) regardless of the configurable dangerous-extensions list. A permissive `accept` policy combined with the default `destination: self@` could otherwise let an attacker overwrite the page's own `.md` and pivot to super-admin via a `process: save` action. This vulnerability is fixed in 9.1.0.",
    "evidence": "osv:CVE-2026-42845",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-42845",
      "aliases": [
        "CVE-2026-42845",
        "GHSA-w4rc-p66m-x6qq"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/getgrav/grav-plugin-form",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1d7124647e8d895e01d105bf353a46358dc25549"
                },
                {
                  "fixed": "48bacc4187e1cff815000e526d5ca2878484867f"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "9.1.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "48bacc4187e1cff815000e526d5ca2878484867f"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "8.2.1",
            "8.2.0",
            "8.1.0",
            "8.0.6",
            "8.0.5",
            "8.0.4",
            "8.0.3",
            "8.0.2",
            "8.0.1",
            "8.0.0",
            "7.4.2",
            "7.4.1",
            "7.4.0",
            "7.3.0",
            "7.2.2",
            "7.2.1",
            "7.2.0",
            "7.1.3",
            "7.1.2",
            "7.1.1",
            "7.1.0",
            "7.0.2",
            "7.0.1",
            "7.0.0",
            "6.0.4",
            "4.0.0",
            "3.0.0-rc.4",
            "3.0.0-rc.3",
            "3.0.0-rc.2",
            "3.0.0-rc.1",
            "3.0.0-beta.5",
            "3.0.0-beta.4",
            "3.0.0-beta.3",
            "3.0.0-beta.2",
            "3.0.0-beta.1",
            "2.8.0-rc.2",
            "2.8.0-rc.1",
            "2.0.8-rc.1",
            "2.0.0-rc.1",
            "1.3.0-rc.4",
            "1.3.0-rc.3",
            "1.3.0-rc.2",
            "1.3.0-rc.1",
            "1.3.0-beta.6",
            "1.3.0-beta.4",
            "1.3.0-beta.3",
            "1.3.0-beta.2",
            "1.3.0-beta.1",
            "0.7.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-42845.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.415814533Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42845.json",
        "https://github.com/getgrav/grav/security/advisories/GHSA-w4rc-p66m-x6qq",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-42845",
        "https://github.com/getgrav/grav-plugin-form/commit/48bacc4187e1cff815000e526d5ca2878484867f"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-73"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42845.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-42845",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517961,
  "published_at": "2026-05-11T15:44:35.524+00:00"
}