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CVE-2026-48988— markdown-it: Quadratic complexity DoS in smartquotes rule via replaceAt string operations

Quick assessment

Affected
markdown-it markdown-it
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Markdown it! markdown-it是Markdown it!组织的一个Markdown解析器与渲染引擎。 Markdown it! markdown-it存在资源管理错误漏洞，该漏洞源于typographer启用时smartquotes规则中存在平方复杂度处理，通过replaceAt()重复修改字符串导致CPU过度消耗，可能造成拒绝服务攻击。

CVSS 5.3 · Medium EPSS 0.43% · P36

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 1

VendorProduct Version RangeStatus
markdown-it markdown-it < 14.2.0 affected
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I. Basic Information for CVE-2026-48988

Vulnerability Information
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Vulnerability Title
markdown-it: Quadratic complexity DoS in smartquotes rule via replaceAt string operations
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Vulnerability Title
Markdown it! markdown-it 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Markdown it! markdown-it是Markdown it!组织的一个Markdown解析器与渲染引擎。 Markdown it! markdown-it存在资源管理错误漏洞，该漏洞源于typographer启用时smartquotes规则中存在平方复杂度处理，通过replaceAt()重复修改字符串导致CPU过度消耗，可能造成拒绝服务攻击。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
markdown-it markdown-it < 14.2.0 -

II. Public POCs for CVE-2026-48988

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III. Intelligence Information for CVE-2026-48988

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Patches & Fixes for CVE-2026-48988 (1)

Vendor Advisories for CVE-2026-48988 (1)

IV. Related Vulnerabilities

Same product: markdown-it
Same vendor: markdown-it
Same weakness: CWE-400

V. Comments for CVE-2026-48988

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