Uncontrolled Resource Consumption in markdown-it
Priority MEDIUM 63CWE-400Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-400.
Summary
markdown-it is a Markdown parser. Prior to version 1.3.2, special patterns with length greater than 50 thousand characterss could slow down the parser significantly. Users should upgrade to version 12.3.2 to receive a patch. There are no known workarounds aside from upgrading.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.02357 83rd percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed markdown-it (markdown-it): 12.3.2markdown-it (npm): 12.3.2
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| markdown-it | markdown-it | before 12.3.2 | 12.3.2 | Patch available | CNA |
| — | markdown-it (npm) | before 12.3.2 | 12.3.2 | Patch available | GHSA-6vfc-qv3f-vr6c |
- markdown-it Vendormarkdown-it Affected before 12.3.2 Fixed in 12.3.2 Patch available CNA
- markdown-it (npm) Vendor— Affected before 12.3.2 Fixed in 12.3.2 Patch available GHSA-6vfc-qv3f-vr6c
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:markdown-it_project:markdown-it:*:*:*:*:*:*:*:* | up to 12.3.1 | Vulnerable | Markdown-it Project |
- cpe:2.3:a:markdown-it_project:markdown-it:*:*:*:*:*:*:*:* Versions up to 12.3.1 Vulnerable ·Markdown-it Project
Remediation
- Fix · CNA markdown-it (markdown-it) Fixed in 12.3.2
- Fix · GHSA-6vfc-qv3f-vr6c markdown-it (npm) Fixed in 12.3.2 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2022-21670
- 2026-10-03 Alias added: GHSA-6vfc-qv3f-vr6c
References
More markdown-it vulnerabilities
- TI-2026-36071 linkify-it: Quadratic algorithmic complexity in LinkifyIt#match scan loop CVSS 4.0HIGH 8.7
- TI-2026-78161 Quadratic-time parsing in markdown-it link reference definitions CVSS 3.1HIGH 7.5
- TI-2026-76535 Quadratic time in markdown-it smartquotes causes denial of service CVSS 3.1HIGH 7.5
- TI-2026-42701 linkify-it: Quadratic-complexity DoS via the `mailto:` validator scan-loop on attacker text CVSS 3.1HIGH 7.5
- TI-2025-07289 Markdown-it 14.1.0 - Cross-site scripting (XSS) CVSS 4.0MEDIUM 6.9
- TI-2026-36244 markdown-it: Quadratic complexity DoS in smartquotes rule via replaceAt string operations CVSS 3.1MEDIUM 5.3
Sources
- CVE-2022-21670 · CVE Program
- CVE-2022-21670 · NVD
- FIRST EPSS
- GHSA-6vfc-qv3f-vr6c · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences