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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-54703
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-14 20:17:47 UTC
Updated2026-10-16 20:02:37 UTC
DescriptionMarkdown 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.

Risk And Classification

Primary CVSS: v4.0 5.8 MEDIUM from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.002160000 probability, percentile 0.111980000 (date 2026-10-16)

Problem Types: CWE-73 | CWE-73 CWE-73: External Control of File Name or Path

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary5.8MEDIUMCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED5.8MEDIUMCVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Passive
Confidentiality
None
Integrity
High
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Shd101wyy Vscode-markdown-preview-enhanced affected < 0.8.30 Not specified

References

ReferenceSourceLinkTags
github.com/shd101wyy/vscode-markdown-preview-enhanced/commit/8bc848b6cbb... [email protected] github.com
github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/tag/0.8.30 [email protected] github.com
github.com/shd101wyy/vscode-markdown-preview-enhanced/security/advisorie... 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/shd101wyy/vscode-markdown-preview-enhanced/pull/2323 [email protected] github.com
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