Published Oct 24, 2026Sources checked Oct 27, 2026
9.4CRITICALCVSS out of 10
What this means
Review the available evidence
CVE-2026-115557 and is rated Critical severity with a CVSS score of 9.4. 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: Oct 27, 2026
Release Notes
Vendor-listed releases
3.12.15-3
CISA KEVNot listedBased on the latest collected catalog
EPSS0.5%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-115557?
Python has added a denylist for known compromised certificates to the "ssl" module to ensure user safety even without certificate revocation configured. Known compromised certificates will automatically be rejected regardless of the SSLContext policy configuration.