Is this vulnerability remotely exploitable?

Yes. If attackers can supply markdown content that will later be rendered by Marky and viewed in a browser or similar environment, they can remotely trigger script execution when a victim opens the malicious file.

What level of access does an attacker need to exploit this issue?

The attacker generally needs the ability to upload, submit, or influence markdown files processed by Marky. This might be as an authenticated user, a collaborator, or anyone with content submission rights, depending on how Marky is integrated.

What is the safest general fix pattern for this vulnerability class?

Introduce a mandatory sanitization and encoding layer between markdown rendering and HTML delivery. That usually means configuring the markdown renderer in a safe mode, running its output through a vetted HTML sanitizer, and ensuring that any remaining dynamic insertion into the DOM uses context-aware escaping.

Severity:

HIGH RISK

(7.2)

Persistent Cross-Site Scripting (CWE-79) in Marky Markdown Rendering

CVE-2021-47839

Published:

Jan 16, 2026

Status:

Awaiting Analysis

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

NDV

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CRITICAL RISK

CRITICAL

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Account Takeover / Loss of Account Control

February 17, 2026

CWE-77;CWE-78

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in node-sonos-http-api TTS Provider for macOS

Remote Code Execution on the Server Host

February 17, 2026

Vulnerability Type

Category:

Cross-Site Scripting (XSS)

CWE:

CWE-79

Impact:

Persistent Cross-Site Scripting with Potential Remote Code Execution

Severity:

HIGH RISK

(7.2)

CVSS Version:

3.1

Vulnerability Type

Category:

Cross-Site Scripting (XSS)

CWE:

CWE-79

Impact:

Persistent Cross-Site Scripting with Potential Remote Code Execution

Severity:

HIGH RISK

(7.2)

CVSS Version:

3.1

Catch This CVE While Code Is Being Written

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Made with Love in San Francisco

355 Bryant St. San Francisco, CA 94107, USA

Ask AI for summary of CodeAnt

Persistent Cross-Site Scripting (CWE-79) in Marky Markdown Rendering

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

Recent Vulnerabilities

CRITICAL RISK

CRITICAL

(9.8)

Missing Authentication for Forgot-Password Email Change API (CWE-306)

HIGH RISK

HIGH

(7.3)

OS Command Injection (CWE-78) in node-sonos-http-api TTS Provider for macOS

Vulnerability Type

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

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