CVE-2025-21728 bpf: Send signals asynchronously if !preemptible

What is CVE-2025-21728?

CVE-2025-21728 is a medium-severity denial of service vulnerability in Linux kernel, published on 27 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

bpf: Send signals asynchronously if !preemptible

BPF programs can execute in all kinds of contexts and when a program running in a non-preemptible context uses the bpf_send_signal() kfunc, it will cause issues because this kfunc can sleep. Change `irqs_disabled()` to `!preemptible()`.

Which versions are affected by CVE-2025-21728?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2025-21728?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2025-21728 being exploited?

There is no known exploitation of CVE-2025-21728 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2025-21728, DEBIAN-CVE-2025-21728, GHSA-f47w-fp34-vr9h, ROOT-OS-UBUNTU-2404-CVE-2025-21728, UBUNTU-CVE-2025-21728.