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CVE-2026-86432— commonmark 2.0.0 before 2.8.4 Denial of Service via XML

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 2.0.0 到 2.8.4 之前的版本中， 存在一个拒绝服务（DoS）漏洞，其问题在于为每个 XML 标签输出与嵌套深度成正比的缩进。攻击者可以通过提供深度嵌套的 Markdown 或 AST 结构，导致二次方内存消耗和输出放大，从而耗尽服务器资源。

CVSS 5.3 · Medium

Affected Version Matrix 2

VendorProduct Version RangeStatus
thephpleague commonmark 2.0.0< 2.8.4 affected
2.8.4 unaffected
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I. Basic Information for CVE-2026-86432

Vulnerability Information
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Vulnerability Title
commonmark 2.0.0 before 2.8.4 Denial of Service via XML
Source: CVE Program / CVE List V5
Vulnerability Description
commonmark versions from 2.0.0 before 2.8.4 contain a denial of service vulnerability in XmlRenderer that emits depth-proportional indentation for every XML tag. Attackers can provide deeply nested Markdown or AST structures to cause quadratic memory consumption and output amplification, exhausting server resources.
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
不对称的资源消耗(放大攻击)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
thephpleague commonmark 2.0.0 ~ 2.8.4 -

II. Public POCs for CVE-2026-86432

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III. Intelligence Information for CVE-2026-86432

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Vendor Advisories for CVE-2026-86432 (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-2026-86428 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

IV. Related Vulnerabilities

Same product: commonmark
Same vendor: thephpleague
Same weakness: CWE-405

V. Comments for CVE-2026-86432

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