---
id: CVE-2026-86432
title: >-
  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
summary: >-
  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 qua…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-405
vendor: thephpleague
product: commonmark
affected:
  - commonmark >= 2.0.0 < 2.8.4
published: '2026-09-07'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T16:18:02.793'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-86432'
references:
  - url: >-
      https://github.com/thephpleague/commonmark/security/advisories/GHSA-mj63-m3rc-8ppr
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/commonmark-2.0.0-before-2.8.4-denial-of-service-via-xml
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-10T14:22:38.482490Z'
epss: 0.00418
epssPercentile: 0.33461
ingestedAt: '2026-09-08T20:10:03.179Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.