CVE-2025-21965: linux kernel vulnerability

CVE-2025-21965: high vulnerability affecting linux kernel. Check CVSS, KEV status, business impact and recommended administrator actions.
CVE-2025-21965CVSS 7.8Linux

CVE-2025-21965: linux kernel vulnerability

CVE-2025-21965: high vulnerability affecting linux kernel. Check CVSS, KEV status, business impact and recommended administrator actions.

CVSS
7.8 HIGH
EPSS
8.88%
Known exploited
not in KEV
Product
linux kernel

What is known

In the Linux kernel, the following vulnerability has been resolved: sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl() If a BPF scheduler provides an invalid CPU (outside the nr_cpu_ids range) as prev_cpu to scx_bpf_select_cpu_dfl() it can cause a kernel crash. To prevent this, validate prev_cpu in scx_bpf_select_cpu_dfl() and trigger an scx error if an invalid CPU is specified.

Business impact

Successful exploitation of CVE-2025-21965, a high vulnerability (CVSS 7.8) affecting linux kernel, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.

Recommended administrator action

Confirm whether linux kernel is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.

Sources

Security newsletter

Get new CVE alerts before they become an incident

We send selected infrastructure threats in English, with practical notes for DataHouse environments.

  • DataHouse: server administration and secure cloud
  • Hostilla.pl: hosting and mail services
  • SecDNS.pl: free DNS security layer