Markdown Preview Enhanced: OS command injection via preview links on Windows
Summary
Markdown Preview Enhanced, a Markdown preview extension for Visual Studio Code, passes link targets from Markdown files to a Windows helper that runs the command through cmd.exe. On Windows, a user who opens an untrusted Markdown file and clicks a crafted external or unsupported-scheme link can cause an attacker-selected command to run with the privileges of the current VS Code user. Exploitation requires only one click in the preview; script execution or malicious workspace settings are not required.
Affected
- shd101wyy vscode-markdown-preview-enhanced versions before 0.8.28 on Windows
Fixed in
- Version 0.8.28 (links and files are opened without a shell)
Workaround
- Unknown.
Exploitation
- No evidence of exploitation in the wild found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- No public exploit found.
Our recommendation
- Update the Visual Studio Code extension to the latest release, at least 0.8.28.
- Identify Windows workstations with the extension installed, especially developer endpoints.
- Until updated, avoid opening Markdown files from untrusted sources and do not click links in their previews.
- Monitor for unexpected child processes spawned by Code.exe.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-7v6f-3vq6-r373 github.com
- Fix commit in vscode-markdown-preview-enhanced github.com
- Pull request #2318 github.com
- Release 0.8.28 github.com
- Upstream crossnote commit 5588ca2 github.com
- Upstream crossnote pull request #442 github.com
- CVE record summary (Vulners) vulners.com
- OpenCVE CVE-2026-54525 app.opencve.io
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 16:40.
Original description (NVD)
Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.28, Markdown Preview Enhanced preview-link handling passes a decoded, Markdown-controlled link target to a Windows file-opening helper that invokes child_process.exec with the start command. When a Windows user opens an untrusted Markdown file and clicks a crafted external or unsupported-scheme link, shell metacharacters in the decoded target are interpreted by cmd.exe as command separators, allowing an attacker-selected command to run with the privileges of the current VS Code user. The attack requires one normal preview-link click but does not require malicious workspace configuration, script execution to be enabled, or additional files. This issue is fixed in version 0.8.28.
NVD references (7)
- https://github.com/shd101wyy/crossnote/commit/5588ca2121c3da43fe331575dc5cf4ef347b91ee
- https://github.com/shd101wyy/crossnote/pull/442
- https://github.com/shd101wyy/crossnote/releases/tag/0.9.29
- https://github.com/shd101wyy/vscode-markdown-preview-enhanced/commit/dcd80281c986293b93d9f1af34ced64dcb230c77
- https://github.com/shd101wyy/vscode-markdown-preview-enhanced/pull/2318
- https://github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/tag/0.8.28
- https://github.com/shd101wyy/vscode-markdown-preview-enhanced/security/advisories/GHSA-7v6f-3vq6-r373
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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