Medium severity · published Sep 7, 2026
CVE-2026-86432
commonmark 2.0.0 before 2.8.4 Denial of Service via XML
5.3
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 36% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CO
commonmark · thephpleague
2.0.0 before 2.8.4 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-86432
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-86432
vendor-advisory
https://github.com/thephpleague/commonmark/security/advisories/GHSA-mj63-m3rc-8ppr
third-party-advisory
https://www.vulncheck.com/advisories/commonmark-2.0.0-before-2.8.4-denial-of-service-via-xml
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