Grav - Stored CSS Injection via Markdown Image resize() Action

{
  "id": "068b8cdfd9b2806ec448afd5fb82e9e982d5bf3a9cb717e9d12269a75181cf86",
  "url": "https://osv.dev/vulnerability/CVE-2026-58657",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Grav - Stored CSS Injection via Markdown Image resize() Action",
    "summary": "Grav before 2.0.0 (affected through 2.0.0-rc.9 and the 2.0 branch) contains a stored CSS injection vulnerability in the Markdown image resize() media action. Prior media hardening rejects direct ?style= payloads and unsafe attribute() fallbacks, but the resize() action in Excerpts::processMediaActions() writes caller-controlled values directly into the image's styleAttributes. A lower-privileged content editor who can edit page Markdown can store a crafted image URL with semicolon-delimited CSS declarations in the resize parameters, which are rendered into the final attribute when a higher-privileged reviewer/admin views the page or preview. This does not require JavaScript execution but enables UI redress/overlay and content-manipulation attacks (e.g., a full-viewport fixed overlay). Fixed in 2.0.0.",
    "evidence": "osv:CVE-2026-58657",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-58657",
      "aliases": [
        "CVE-2026-58657",
        "GHSA-ffmg-hfvg-jhg9"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/getgrav/grav",
              "type": "GIT",
              "events": [
                {
                  "introduced": "e03d29aa0d3ece16d73c1ffccfa78df8bf5f28b8"
                },
                {
                  "fixed": "bb4022f44b882ca4615188f4da5a0d646cef02ce"
                },
                {
                  "fixed": "6582166173bb8eb5869d96aea384e0e73777c94c"
                },
                {
                  "fixed": "e03d29aa0d3ece16d73c1ffccfa78df8bf5f28b8"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "2.0.0-rc.9"
                      },
                      {
                        "fixed": "2.0.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "6582166173bb8eb5869d96aea384e0e73777c94c"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e03d29aa0d3ece16d73c1ffccfa78df8bf5f28b8"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-58657.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:29.355394274Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/58xxx/CVE-2026-58657.json",
        "https://github.com/getgrav/grav/security/advisories/GHSA-ffmg-hfvg-jhg9",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-58657",
        "https://www.vulncheck.com/advisories/grav-stored-css-injection-via-markdown-image-resize-action",
        "https://github.com/getgrav/grav/commit/6582166173bb8eb5869d96aea384e0e73777c94c",
        "https://github.com/getgrav/grav/commit/e03d29aa0d3ece16d73c1ffccfa78df8bf5f28b8"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-79"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/58xxx/CVE-2026-58657.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-58657",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 496244,
  "published_at": "2026-07-08T13:49:12.183+00:00"
}