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CVE-2026-86430— league/commonmark before 2.9.1 Denial of Service via parsing

Quick assessment

Affected
thephpleague commonmark
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.

以下是该漏洞描述信息的中文翻译： 英文原文： league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. At

CVSS 7.5 · High

Affected Version Matrix 2

VendorProduct Version RangeStatus
thephpleague commonmark 0.6.0< 2.9.1 affected
2.9.1 unaffected
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I. Basic Information for CVE-2026-86430

Vulnerability Information
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Vulnerability Title
league/commonmark before 2.9.1 Denial of Service via parsing
Source: CVE Program / CVE List V5
Vulnerability Description
league/commonmark versions before 2.9.1 contain multiple denial of service vulnerabilities in fenced code block detection, reference link label lookup, and emphasis delimiter processing that perform super-linear work on crafted input. Attackers can submit specially crafted Markdown with long backtick runs, nested brackets, or delimiter sequences to consume disproportionate CPU time and prevent legitimate requests from completing.
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:H
Source: CVE Program / CVE List V5
Vulnerability Type
算法复杂性
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
thephpleague commonmark 0.6.0 ~ 2.9.1 -

II. Public POCs for CVE-2026-86430

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III. Intelligence Information for CVE-2026-86430

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Vendor Advisories for CVE-2026-86430 (2)

Same Patch Batch · thephpleague · 2026-09-07 · 8 CVEs total

CVE-2026-86429 7.5 HIGH commonmark before 2.9.1 Denial of Service via SmartPunct and Attributes
CVE-2026-86435 7.5 HIGH commonmark 1.5.0 before 2.8.4 Denial of Service via Footnote
CVE-2026-86434 7.5 HIGH commonmark 2.0.0 through 2.8.3 Denial of Service via Slug Collision
CVE-2026-86433 7.5 HIGH commonmark 1.5.0 before 2.8.4 Denial of Service via Attributes
CVE-2026-86428 7.5 HIGH commonmark 1.5.0 before 2.10.0 Denial of Service via Attributes
CVE-2026-86431 7.2 HIGH commonmark before 2.9.1 XSS via AttributesExtension form feed bypass
CVE-2026-86432 5.3 MEDIUM commonmark 2.0.0 before 2.8.4 Denial of Service via XML

IV. Related Vulnerabilities

Same product: commonmark
Same vendor: thephpleague
Same weakness: CWE-407

V. Comments for CVE-2026-86430

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