Description
markdown-it is a Markdown parser. Prior to 14.3.2 and 15.0.2, when typographer: true is enabled, specially crafted Markdown can cause quadratic processing time in the smartquotes rule, potentially leading to denial of service in applications processing untrusted input. Many opening double quotes followed by unmatched closing single quotes cause repeated scans of the entire opener stack. The same issue occurs with the quote types reversed. The default configuration (typographer: false) is not affected, but this option is enabled with high probability. This issue is fixed in versions 14.3.2 and 15.0.2.
Published: 2026-10-19
Score: 7.5 High
EPSS: n/a
KEV: No
Impact: Denial of Service
Action: Apply Patch
AI Analysis

Impact

A flaw in the smartquotes processing of markdown-it triggers a quadratic rescanning of the opener stack whenever many opening quotes of one type are followed by unmatched closing quotes of another type while typographer mode is enabled. This causes excessive CPU usage and can lock the parsing thread, resulting in denial of service. The weakness involves resource exhaustion (CWE-400) and unnecessary complexity (CWE-407).

Affected Systems

The attacker can affect any installation of markdown-it prior to release 14.3.2 or 15.0.2. Vendors include markdown-it:markdown-it, and any software embedding that library with typographer mode activated is vulnerable.

Risk and Exploitability

The vulnerability carries a CVSS score of 7.5 and is not listed in KEV. EPSS data is not available, but the attack path is straightforward: an adversary can supply crafted Markdown containing many unmatched quotes to any input handling process that relies on the affected library. Because no authentication is required to submit Markdown, the threat surface is large.

Generated by OpenCVE AI on October 19, 2026 at 18:22 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Upgrade markdown-it to version 14.3.2 or later, or 15.0.2 or later.
  • If an upgrade is not immediately possible, disable typographer mode or the smartquotes rule to eliminate the vulnerable processing path.
  • Implement input size or quote count limits on Markdown content to reduce the impact of a potential denial of service.

Generated by OpenCVE AI on October 19, 2026 at 18:22 UTC.

Tracking

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Advisories

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History

Mon, 19 Oct 2026 18:00:00 +0000

Type Values Removed Values Added
Description markdown-it is a Markdown parser. Prior to 14.3.2 and 15.0.2, smartquotes is affected: many opening quotes of one type followed by unmatched closing quotes of the other type cause the smartquotes rule to repeatedly scan the entire opener stack, resulting in quadratic processing time. The root cause is each mismatched quote closer repeatedly scans the opener stack for a compatible quote type. The attack mechanism is quadratic rescanning of the quote opener stack. The affected identifiers are smartquotes and typographer. The trigger conditions are attacker-controlled Markdown with many openers of one quote type and unmatched closers of the other type and typographer mode is enabled. The impact is denial of service through excessive parsing time. The vulnerable path requires typographer mode; disabling typographer or the smartquotes rule prevents the affected processing. This issue is fixed in versions 14.3.2 and 15.0.2. markdown-it is a Markdown parser. Prior to 14.3.2 and 15.0.2, when typographer: true is enabled, specially crafted Markdown can cause quadratic processing time in the smartquotes rule, potentially leading to denial of service in applications processing untrusted input. Many opening double quotes followed by unmatched closing single quotes cause repeated scans of the entire opener stack. The same issue occurs with the quote types reversed. The default configuration (typographer: false) is not affected, but this option is enabled with high probability. This issue is fixed in versions 14.3.2 and 15.0.2.

Mon, 19 Oct 2026 17:45:00 +0000

Type Values Removed Values Added
Description markdown-it is a Markdown parser. Prior to 14.3.2 and 15.0.2, smartquotes is affected: many opening quotes of one type followed by unmatched closing quotes of the other type cause the smartquotes rule to repeatedly scan the entire opener stack, resulting in quadratic processing time. The root cause is each mismatched quote closer repeatedly scans the opener stack for a compatible quote type. The attack mechanism is quadratic rescanning of the quote opener stack. The affected identifiers are smartquotes and typographer. The trigger conditions are attacker-controlled Markdown with many openers of one quote type and unmatched closers of the other type and typographer mode is enabled. The impact is denial of service through excessive parsing time. The vulnerable path requires typographer mode; disabling typographer or the smartquotes rule prevents the affected processing. This issue is fixed in versions 14.3.2 and 15.0.2.
Title markdown-it: Quadratic complexity in smartquotes with unmatched closing quotes
Weaknesses CWE-400
CWE-407
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-19T18:22:54.696Z

Reserved: 2026-10-16T17:52:09.081Z

Link: CVE-2026-111759

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-19T18:17:00.570

Modified: 2026-10-19T18:17:00.570

Link: CVE-2026-111759

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-19T18:30:02Z

Weaknesses
  • CWE-400

    Uncontrolled Resource Consumption

  • CWE-407

    Inefficient Algorithmic Complexity