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Medium, CVSS 5.3amended

Uncontrolled Resource Consumption in markdown-it

CVE-2022-21670GHSA-6vfc-qv3f-vr6c

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (markdown-it 12.3.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
EPSS
  • CVE-2022-21670: 2.36% estimated exploitation activity in the next 30 days; percentile 83.77 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Impact Special patterns with length 50K chars can slow down parser significantly. Patches Upgrade to v12.3.2+ Workarounds No. References Fix + test sample: https://github.com/markdown-it/markdown-it/commit/ffc49ab46b5b751cd2be0aabb146f2ef84986101

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-6vfc-qv3f-vr6c

  2. Revision 1 · created ·

    Published from osv record GHSA-6vfc-qv3f-vr6c

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2022-21670

Advisory: Uncontrolled Resource Consumption in markdown-it
IDs: CVE-2022-21670, GHSA-6vfc-qv3f-vr6c
Record: https://patchnext.com/advisories/cve-2022-21670 (revision 2, source checked 26 Oct 2026, 12:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: markdown-it 12.3.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm markdown-it: affected < 12.3.2; fixed in 12.3.2

## Suggested inspection (read-only)
- `npm ls markdown-it --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on markdown-it.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-6vfc-qv3f-vr6c (OSV record GHSA-6vfc-qv3f-vr6c lists affected ranges: npm markdown-it >=0 <12.3.2 (fixed))
- Verified: https://github.com/advisories/GHSA-6vfc-qv3f-vr6c (GitHub-reviewed advisory GHSA-6vfc-qv3f-vr6c lists affected ranges: npm markdown-it >=0 <12.3.2)

Commands are suggestions: review each one before running it.

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