CVE-2025-21934 and is rated High severity with a CVSS score of 7.8. 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 12, 2026
CBL-Mariner Releases
Vendor-listed releases
5.15.180.1-1
6.6.85.1-2
CISA KEVNot listedBased on the latest collected catalog
EPSS0.2%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2025-21934?
In the Linux kernel, the following vulnerability has been resolved:
rapidio: fix an API misues when rio_add_net() fails
rio_add_net() calls device_register() and fails when device_register() fails. Thus, put_device() should be used rather than kfree().
Add "mport->net = NULL;" to avoid a use after free issue.