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CVE-2026-86428— commonmark 1.5.0 before 2.10.0 Denial of Service via Attributes

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.

commonmark 从 1.5.0 起至 2.10.0 之前的版本中， 在处理具有不同名称的属性时存在服务拒绝（DoS）漏洞。攻击者可以提交包含大量不同属性名称的 Markdown 内容，从而导致属性合并与过滤操作出现二次方级时间复杂度，消耗不成比例的 CPU 资源，进而导致正常请求无法完成处理。

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 2

VendorProduct Version RangeStatus
thephpleague commonmark 1.5.0< 2.10.0 affected
2.10.0 unaffected
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I. Basic Information for CVE-2026-86428

Vulnerability Information
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Vulnerability Title
commonmark 1.5.0 before 2.10.0 Denial of Service via Attributes
Source: CVE Program / CVE List V5
Vulnerability Description
commonmark versions from 1.5.0 before 2.10.0 contain a denial of service vulnerability in the AttributesExtension when processing distinctly-named attributes. Attackers can submit Markdown with numerous distinct attribute names to cause quadratic-time attribute merging and filtering, consuming disproportionate CPU resources and preventing 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 1.5.0 ~ 2.10.0 -

II. Public POCs for CVE-2026-86428

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III. Intelligence Information for CVE-2026-86428

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Vendor Advisories for CVE-2026-86428 (2)

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

CVE-2026-86430 7.5 HIGH league/commonmark before 2.9.1 Denial of Service via parsing
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-2026-86431 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-2026-86428

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