dbcve.org
Code InjectionWeakness · CWE-94

CVE-2026-49493

HIGH · 8.8 CVSS v3.1 Published 2026-06-05
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Markdown Preview Enhanced before 0.8.28 parses Bitfield fenced code blocks with interpretJS(), which evaluates the block content as code via vm.runInNewContext(), allowing arbitrary code execution. A crafted markdown document containing a malicious bitfield code block executes attacker-controlled code on the server side when the document is rendered or exported. Fixed in 0.8.28 by parsing bitfield register definitions with JSON5.parse(), since they are purely data.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Markdown Preview Enhanced before version 0.8.28 contains a critical code injection vulnerability in its Bitfield fenced code block parser. The plugin incorrectly evaluates Bitfield code block content as executable JavaScript via Node.js vm.runInNewContext(), allowing attackers to execute arbitrary server-side code by embedding malicious JavaScript in markdown documents.

MitigationUpgrade Markdown Preview Enhanced to version 0.8.28 or later, which replaces the unsafe vm.runInNewContext() evaluation with JSON5.parse() for safe data parsing of Bitfield register definitions.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Markdown Preview Enhanced version
    Use the extension manager for your IDE (e.g., 'code --list-extensions' for VS Code, or check extension details via the GUI) to determine the installed version of the markdown-preview-enhanced extension
    Affected if Version is before 0.8.28
  2. Locate the Bitfield parser component
    Search the Markdown Preview Enhanced installation directory for files related to Bitfield parsing; the plugin includes a Bitfield fenced code block parser that processes special code blocks
    Affected if A Bitfield parser file exists in the extension installation
  3. Inspect the parser for unsafe evaluation
    Open the Bitfield parser source file and search for 'vm.runInNewContext' - this Node.js function evaluates strings as executable code and is the vulnerability vector
    Affected if The code contains vm.runInNewContext() being called on Bitfield code block content
  4. Detect use of Bitfield fenced code blocks
    Search your markdown files for fenced code blocks tagged with 'bitfield' (```bitfield) - this is the feature that triggers the vulnerable parser
    Affected if Markdown files contain ```bitfield code blocks that would be processed by the vulnerable parser

You are affected if Markdown Preview Enhanced version is below 0.8.28 AND the Bitfield parser uses vm.runInNewContext AND you use Bitfield fenced code blocks in your markdown documents.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Markdown Preview Enhanced to version 0.8.28 or later, which replaces the unsafe vm.runInNewContext() evaluation with JSON5.parse() for safe data parsing of Bitfield register definitions.

Recommended fix High confidence

Version 0.8.28 or later of markdown-preview-enhanced

  1. 1. Identify the environment where Markdown Preview Enhanced is installed (e.g., VS Code extension, Node.js project)
  2. 2. For VS Code: Open the Extensions view, search for 'Markdown Preview Enhanced', and update to version 0.8.28 or later
  3. 3. For Node.js project: Run 'npm install [email protected]' or 'npm update markdown-preview-enhanced'
  4. 4. Verify the installed version matches or exceeds 0.8.28 using the package manager
  5. 5. Test that markdown documents with bitfield code blocks render correctly after the upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-49493 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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