markdown-it: Quadratic complexity DoS in smartquotes rule via replaceAt string operations
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
- Partial Red Hat: 6 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.
Summary
markdown-it is a Markdown parser. Versions 14.1.1 and below contain a denial-of-service vulnerability when typographer: true is enabled, due to quadratic (O(n^2)) processing in the smartquotes rule. The issue stems from repeatedly modifying strings with replaceAt(), which performs O(n) slicing and concatenation per quote character. This can cause excessive CPU consumption when parsing quote-heavy, user-supplied markdown and may let attackers degrade or disrupt service availability. Although typographer is disabled by default, many production apps enable it for smart typography, making the issue relevant. This issue has been fixed in version 14.2.0.
Why it matters now
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 14.2.0 | 14.2.0 | Patch available | CNA |
| — | markdown-it (npm) | before 14.2.0 | 14.2.0 | Patch available | GHSA-6v5v-wf23-fmfq |
- markdown-it Vendormarkdown-it Affected before 14.2.0 Fixed in 14.2.0 Patch available CNA
- markdown-it (npm) Vendor— Affected before 14.2.0 Fixed in 14.2.0 Patch available GHSA-6v5v-wf23-fmfq
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:markdown-it_project:markdown-it:*:*:*:*:*:*:*:* | before 14.2.0 | Vulnerable | Markdown-it Project |
- cpe:2.3:a:markdown-it_project:markdown-it:*:*:*:*:*:*:*:* Versions before 14.2.0 Vulnerable ·Markdown-it Project
Remediation
- Fix · CNA markdown-it (markdown-it) Fixed in 14.2.0
- Fix · GHSA-6v5v-wf23-fmfq markdown-it (npm) Fixed in 14.2.0 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Build of Podman Desktop | Affected | No fix yet: Fix deferred |
| Red Hat Ceph Storage 9 | Affected | No fix yet: Fix deferred |
| Red Hat Developer Hub 1 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Dev Spaces | Affected | No fix yet: Fix deferred |
| Self-service automation portal 2 | Affected | No fix yet: Fix deferred |
Not affected: 1 product
- Red Hat Hardened Images
Timeline
- 2026-10-02 Threatist record created from CVE-2026-48988
- 2026-10-03 Alias added: GHSA-6v5v-wf23-fmfq
- 2026-10-27 Affected versions changed · Red Hat
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-2022-06047 Uncontrolled Resource Consumption in markdown-it CVSS 3.1MEDIUM 5.3
Sources
- CVE-2026-48988 · CVE Program
- CVE-2026-48988 · NVD
- FIRST EPSS
- GHSA-6v5v-wf23-fmfq · GitHub Advisory Database · CC BY 4.0
- CVE-2026-48988 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences