Published Jun 17, 2025Sources checked Nov 11, 2026
4.3MEDIUMCVSS out of 10
What this means
Review the available evidence
CVE-2025-6069 and is rated Medium severity with a CVSS score of 4.3. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
What to do next
Remediation and response
Microsoft Security Response Center guidance
Vendor revision: Aug 13, 2026
CBL-Mariner Releases
Vendor-listed releases
3.9.19-14
3.12.9-3
CISA KEVNot listedBased on the latest collected catalog
EPSS0.6%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2025-6069?
The html.parser.HTMLParser class had worse-case quadratic complexity when processing certain crafted malformed inputs potentially leading to amplified denial-of-service.