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CVE-2025-21965

7.8 · HIGH

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 ran…

Published Apr 1, 2025CWE-476EPSS 0.20%

Overview

CVE-2025-21965 is a high-severity vulnerability. It was published on April 1, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/515680e76c536dd4aa8e2b5d674b0d441baddf5bRefgit.kernel.org/stable/c/752b56bb76e2471197d25d6948d85753043b10daRefgit.kernel.org/stable/c/9360dfe4cbd62ff1eb8217b815964931523b75b3

How CyberStrike helps

Frequently asked questions

What is CVE-2025-21965?

CVE-2025-21965 is a high-severity vulnerability. It was published on April 1, 2025 and has a CVSS 3.1 base score of 7.8 (HIGH).

How severe is CVE-2025-21965?

This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-21965?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-21965?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-21965 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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