VYPR
← All advisories
Medium severity5.5NVD Advisory· Published Feb 27, 2025· Updated May 12, 2026

CVE-2025-21728

CVE-2025-21728

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().

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

A Linux kernel vulnerability allows BPF programs to call bpf_send_signal() in non-preemptible contexts, potentially causing a kernel panic.

Vulnerability

Description

In the Linux kernel, the bpf_send_signal() kfunc could be invoked from BPF programs running in non-preemptible contexts (e.g., tracepoints or kprobes with preemption disabled). The original check used irqs_disabled(), which is insufficient to detect all sleeping-prohibited contexts, leading to a potential sleep-in-atomic bug. The fix replaces irqs_disabled() with !preemptible() to correctly identify when sleeping is unsafe.

Exploitation

An attacker with the ability to load and execute BPF programs (requiring CAP_BPF or similar privileges) can trigger this vulnerability by running a BPF program in a non-preemptible context and calling bpf_send_signal(). This can cause the kernel to attempt a sleep operation while preemption is disabled, resulting in a kernel panic or undefined behavior.

Impact

Successful exploitation leads to a denial of service (system crash). The CVSS v3 score is 5.5 (Medium), reflecting local access and low privileges. Siemens has listed this CVE in advisories SSA-265688 [1] and SSA-082556 [2], confirming that affected products include SIMATIC S7-1500 TM MFP and CPU families running the GNU/Linux subsystem.

Mitigation

The fix is included in stable kernel updates; the relevant commits are available in the kernel repository [3][4]. Users should apply vendor patches or update to a kernel version containing the fix. Siemens recommends updating the affected products as per their security advisories [1][2].

References
  1. SSA-265688
  2. SSA-082556
  3. Making sure you're not a bot!
  4. Making sure you're not a bot!

AI Insight generated on May 20, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected products

138

Patches

0

No patches discovered yet.

Vulnerability mechanics

AI mechanics synthesis has not run for this CVE yet.

References

12

News mentions

0

No linked articles in our index yet.