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Uncontrolled Resource ConsumptionWeakness · CWE-400

CVE-2025-9670

MEDIUM · 5.3 CVSS v3.1 Published 2025-08-29
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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
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.

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 · moderate confidence

A Regular Expression Denial of Service (ReDoS) vulnerability exists in turndown library up to version 7.2.1 in the src/commonmark-rules.js file. The regular expressions used for parsing have inefficient complexity that can be exploited with specially crafted HTML input, causing excessive backtracking and potential denial of service.

MitigationUpdate turndown to a version beyond 7.2.1 when available. As a workaround, implement input length limits or content sanitization before passing HTML to the library to reduce the attack surface.

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
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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

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. Check installed turndown version
    Run 'npm list turndown' or inspect package.json dependencies to find the installed version
    Affected if The installed version is 7.2.1 or lower
  2. Locate the vulnerable file
    Search for src/commonmark-rules.js in the node_modules/turndown directory
    Affected if The file exists and is present in the turndown package being used
  3. Search your codebase for 'turndown' import/require statements and verify HTML input is passed to the turndown() parse function
    Affected if The application imports turndown and passes HTML content to its parsing method

You are affected if your project uses turndown version 7.2.1 or lower and passes HTML input to the library for conversion.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Update turndown to a version beyond 7.2.1 when available. As a workaround, implement input length limits or content sanitization before passing HTML to the library to reduce the attack surface.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing5.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,970
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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-2025-9670 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data