# CVE-2026-99237: Linux kernel tracing use-after-free in last boot data reset

Source: https://junglewise.ai/threats/cve-2026-99237-in-the-linux-kernel-the-following-vulnerability-has-been-resolved  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-02. Updated: 2026-11-02  
License: CC BY 4.0 with a link back

CVE-2026-99237 · Severity: high · CVSS 7.8 · Published 2026-11-02

A race condition in the Linux kernel's tracing subsystem allows multiple processes to simultaneously free the same memory resource when resetting trace data from boot, leading to memory corruption and potential system instability. An attacker with local access to the tracing interface could trigger this condition, causing crashes or potentially executing arbitrary code with kernel privileges.

Technologies: [Linux Kernel](https://junglewise.ai/threats/technologies/kernel). Vendors: [Linux](https://junglewise.ai/threats/vendors/linux).

## Quick answers

**Is CVE-2026-99237 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-99237 being exploited in the wild.

**How severe is CVE-2026-99237?** High severity, with a CVSS score of 7.8, published 2 November 2026.

**Which products and versions are affected?** Linux Kernel versions before fix commit 5a6bd62f09147b49b31fd19d4eba122cb5f941a1.

**Is there a fix for CVE-2026-99237?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-99237 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-99237?** Check whether you run Linux Kernel at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A use-after-free vulnerability exists in update_last_data_if_empty() called from tracing_open(), tracing_read_pipe(), and tracing_buffers_read() without proper synchronization via trace_types_lock. Two concurrent readers can both pass the LAST_BOOT test and double-free module_delta, while a module notifier can update the pointer during or after deallocation. The fix introduces trace_types_lock synchronization in the affected read paths.

## Affected products

- Linux Linux kernel versions before fix commit 5a6bd62f09147b49b31fd19d4eba122cb5f941a1

## Timeline

- 2026-11-02: disclosed
- 2026-10-16: other: Patch commit authored

## References

- [https://git.kernel.org/stable/c/1f06cfe0b60a878619d1d8efe1cd0f515b7dc2aa](https://git.kernel.org/stable/c/1f06cfe0b60a878619d1d8efe1cd0f515b7dc2aa)
- [https://git.kernel.org/stable/c/92b69f6db640dadc0851762ee2e12db99f083cad](https://git.kernel.org/stable/c/92b69f6db640dadc0851762ee2e12db99f083cad)

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