CVE-2026-86432

commonmark 2.0.0 before 2.8.4 Denial of Service via XML

MEDIUM
5.3
CVSS Score
Published: September 7, 2026 at 12:53 PM UTC
Updated: October 8, 2026 at 04:17 PM UTC
1 product affected across 1 vendorCommonmark

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.0.0 ≤ v < 2.8.42.0.0
Vendor states this is fixed in 2.8.4 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-405

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