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Medium

Markdown Preview Enhanced: Arbitrary File Write via updateMarkdown Command Without Path Validation

Type: advisorySources: OSV

Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.30, the _crossnote.updateMarkdown command in Markdown Preview Enhanced accepts an arbitrary URI and attacker-controlled content, then passes them to vscode.workspace.fs.writeFile without validating that the target is the Markdown file represented by the current preview. JavaScript already executing in the preview webview can invoke this command through the extension message bridge and write any file permitted by the VS Code user's operating-system privileges, including user configuration, startup, source, and build files. This file-write vulnerability requires a separate webview JavaScript execution path, such as the independently tracked head.html injection and blind command-dispatch weaknesses. This issue is fixed in version 0.8.30.

Products
Not specified
Affected versions
Not specified
Fixed versions
Not specified
CVEs
CVE-2026-54703
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 05:06 UTC · Revision 1

Source evidence

Markdown Preview Enhanced: Arbitrary File Write via updateMarkdown Command Without Path Validation

core-osv · Original source

Published 14 Oct 2026, 19:09 UTC

Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.30, the _crossnote.updateMarkdown command in Markdown Preview Enhanced accepts an arbitrary URI and attacker-controlled content, then passes them to vscode.workspace.fs.writeFile without validating that the target is the Markdown file represented by the current preview. JavaScript already executing in the preview webview can invoke this command through the extension message bridge and write any file permitted by the VS Code user's operating-system privileges, including user configuration, startup, source, and build files. This file-write vulnerability requires a separate webview JavaScript execution path, such as the independently tracked head.html injection and blind command-dispatch weaknesses. This issue is fixed in version 0.8.30.

osv:CVE-2026-54703
Complete source record
{
  "id": "2fc674ff12beec732ac134a208ef199c23b0035be55361385105fb39205b9b73",
  "url": "https://osv.dev/vulnerability/CVE-2026-54703",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Markdown Preview Enhanced: Arbitrary File Write via updateMarkdown Command Without Path Validation",
    "summary": "Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.30, the _crossnote.updateMarkdown command in Markdown Preview Enhanced accepts an arbitrary URI and attacker-controlled content, then passes them to vscode.workspace.fs.writeFile without validating that the target is the Markdown file represented by the current preview. JavaScript already executing in the preview webview can invoke this command through the extension message bridge and write any file permitted by the VS Code user's operating-system privileges, including user configuration, startup, source, and build files. This file-write vulnerability requires a separate webview JavaScript execution path, such as the independently tracked head.html injection and blind command-dispatch weaknesses. This issue is fixed in version 0.8.30.",
    "evidence": "osv:CVE-2026-54703",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-54703",
      "aliases": [
        "CVE-2026-54703",
        "GHSA-82rc-7g3m-2c42"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/shd101wyy/vscode-markdown-preview-enhanced",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "8bc848b6cbb42b9f35a0f95f7c3bf29b8302970e"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.8.30"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "8bc848b6cbb42b9f35a0f95f7c3bf29b8302970e"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "8bc848b6cbb42b9f35a0f95f7c3bf29b8302970e"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "0.8.30"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.8.30"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "versions": [
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            "0.8.28",
            "0.8.27",
            "0.8.26",
            "0.8.25",
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            "0.8.23",
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            "0.8.15",
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            "0.8.5",
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            "0.8.3",
            "0.8.2",
            "0.8.1",
            "0.8.0",
            "0.7.10",
            "0.7.9",
            "0.7.8",
            "0.7.7",
            "v0.7.6",
            "v0.7.5",
            "v0.7.4",
            "v0.7.3",
            "v0.7.2",
            "v0.7.1",
            "v0.7.0",
            "v0.6.10",
            "v0.6.8",
            "v0.6.7",
            "v0.6.6",
            "v0.6.5",
            "v0.6.3",
            "v0.6.2",
            "v0.6.1",
            "v0.6.0",
            "v0.5.22",
            "v0.5.21",
            "v0.5.20",
            "v0.5.18",
            "v0.5.17",
            "v0.5.16",
            "v0.5.15",
            "v0.5.14",
            "v0.5.13",
            "v0.5.12",
            "v0.5.11",
            "v0.5.10",
            "v0.5.9",
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            "v0.5.3",
            "v0.5.2",
            "v0.5.1",
            "0.5.1",
            "0.5.0",
            "v0.4.3",
            "0.4.3",
            "v0.4.2",
            "0.4.2",
            "v0.4.1",
            "0.4.1",
            "0.4.0",
            "v0.3.13",
            "0.3.13",
            "v0.3.12",
            "0.3.12",
            "0.3.11",
            "0.3.10",
            "0.3.9",
            "0.3.8",
            "0.3.7",
            "0.3.6",
            "0.3.5",
            "0.3.4",
            "0.3.3",
            "0.3.2",
            "0.3.1",
            "0.3.0",
            "0.2.9",
            "0.2.8",
            "0.2.7",
            "0.2.6",
            "0.2.5",
            "0.2.4",
            "0.2.3",
            "0.2.2",
            "0.2.1",
            "0.2.0",
            "0.1.9",
            "0.1.8",
            "0.1.7",
            "0.1.6",
            "0.1.5",
            "0.1.4",
            "0.1.3",
            "0.1.2",
            "0.1.1",
            "0.1.0",
            "0.0.9",
            "0.0.8"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-54703.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.079297214Z",
      "provider": "osv",
      "references": [
        "https://github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/tag/0.8.30",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54703.json",
        "https://github.com/shd101wyy/vscode-markdown-preview-enhanced/security/advisories/GHSA-82rc-7g3m-2c42",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-54703",
        "https://github.com/shd101wyy/vscode-markdown-preview-enhanced/commit/8bc848b6cbb42b9f35a0f95f7c3bf29b8302970e",
        "https://github.com/shd101wyy/vscode-markdown-preview-enhanced/pull/2323"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-73"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54703.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-54703",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492648,
  "published_at": "2026-10-14T19:09:50.323+00:00"
}