Resource exhaustion in Markdown-It
CVE-2026-48988
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.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.004 (34.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 34.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.001
Affected products
- Markdown-It — versions < 14.2.0
- Markdown-It Project
Weakness classification (CWE)
References
- github.com/markdown-it/markdown-it/security/advisories/GHSA-6v5v-wf23-fmfq (Exploit, Mitigation, Vendor Advisory)
- github.com/markdown-it/markdown-it/commit/9ce2087562c45d1e5ddd9f76b990f4b3fbe04… (Patch)
Frequently asked questions
- What is CVE-2026-48988?
- CVE-2026-48988 is a medium-severity vulnerability in Markdown-It, classified under Uncontrolled Resource Consumption. CVSS score: 5.3/10. Published 2026-06-17.
- How severe is CVE-2026-48988?
- Medium severity. CVSS v3 base score is 5.3 out of 10.