Vulnerability · Published Jun 17, 2026 · Assigned by GitHub_M
CVE-2026-48988markdown-it: Quadratic complexity DoS in smartquotes rule via replaceAt string operations
Medium 5.3
In plain English
A medium-severity uncontrolled resource consumption in markdown-it from markdown-it. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | node-markdown-it | no fix listed | DEBIAN-CVE-2026-48988 |
| Debian:13 | node-markdown-it | no fix listed | DEBIAN-CVE-2026-48988 |
| Debian:14 | node-markdown-it | 22.2.3+dfsg+~12.2.3-5 | DEBIAN-CVE-2026-48988 |
| Ubuntu:22.04:LTS | node-markdown-it | no fix listed | UBUNTU-CVE-2026-48988 |
| Ubuntu:24.04:LTS | node-markdown-it | no fix listed | UBUNTU-CVE-2026-48988 |
| Ubuntu:25.10 | node-markdown-it | no fix listed | UBUNTU-CVE-2026-48988 |
| Ubuntu:26.04:LTS | node-markdown-it | no fix listed | UBUNTU-CVE-2026-48988 |
| Ubuntu:26.10 | node-markdown-it | no fix listed | UBUNTU-CVE-2026-48988 |
| npm | markdown-it | 14.2.0 | GHSA-6v5v-wf23-fmfq |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| markdown-it | markdown-it | < 14.2.0 |
Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L