---
id: "CVE-2026-99237"
kind: "vulnerability"
aliases: ["CVE-2026-99237"]
title: "Linux kernel: tracing readers can free boot data twice, causing memory corruption"
severity: "high"
cvss: 7.8
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "linux-kernel", "fixed": [], "affected": "kernels containing commit 32dc0042528d and not 5a6bd62f0914; exact versions unknown", "ecosystem": "linux"}]
ecosystems: []
tags: ["infrastructure", "kernel", "linux", "local", "self-hosted", "tracing"]
not_affected_if: ["tracefs-restricted"]
published_at: "2026-11-02T16:17:49+00:00"
first_seen_at: "2026-11-02T16:24:06+00:00"
updated_at: "2026-11-02T16:27:35+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99237", "first_seen_at": "2026-11-02T16:24:06+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-11-02T16:27:35+00:00"}]
---

# Linux kernel: tracing readers can free boot data twice, causing memory corruption

Linux kernel tracing: update_last_data_if_empty() runs from tracing_open() with O_TRUNC, tracing_read_pipe() and tracing_buffers_read() without trace_types_lock. Two readers can free module_delta twice, and a module notifier can update it while it is being freed. Fixed upstream by commit 5a6bd62f0914; stable backports for 6.18 and 7.2 are in review.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- linux:linux-kernel affected kernels containing commit 32dc0042528d and not 5a6bd62f0914; exact versions unknown fixed ?

## How to check

- Run uname -r, then check your distribution's kernel changelog or security tracker for CVE-2026-99237 or upstream commit 5a6bd62f0914.
- The bug is in code added by commit 32dc0042528d (last-boot trace buffer reset), so a kernel without that commit is not affected. The affected version range is unknown from the sources read.
- Check who can open tracefs: ls -ld /sys/kernel/tracing. The sources do not say whether unprivileged users can reach the paths; the CVSS vector is local, low privileges.

## Fix

Mainline commit 5a6bd62f09147b49b31fd19d4eba122cb5f941a1 takes trace_types_lock in the reader paths. It is queued as a stable review patch for 6.18 and 7.2. A released fixed version is not yet confirmed: install your distribution's kernel update that lists CVE-2026-99237.

## Timeline

- 2026-11-02T16:24:06+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99237
- 2026-11-02T16:27:35+00:00 analyst — Read the maintainer patch (Rostedt for-next, 2026-10-20) and the 6.18/7.2 stable review patches. Mainline fix is commit 5a6bd62f0914 (David Carlier), Fixes: 32dc0042528d. No released fixed version or affected range was stated in sources read; NVD page was empty. Not stated whether tracefs is reachable by unprivileged users. Nothing verified.

## Documents

- [advisory] tracing: Hold trace_types_lock when resetting last boot data from readers (Rostedt for-next, 2026-10-20) https://lore.landau.one/lkml/20261020122011.033386537@kernel.org/
- [fix] 7.2-stable review patch: upstream commit 5a6bd62f0914 https://ci.syzbot.org/patches/9325c52c-52fe-4ad0-b461-f0734828d66a
- [fix] 6.18-stable review patch: upstream commit 5a6bd62f0914 https://ci.syzbot.org/patches/dbb9227c-7224-441f-877e-68d09c46c916

## From the sources

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

tracing: Hold trace_types_lock when resetting last boot data from readers

update_last_data_if_empty() is called from tracing_open() with O_TRUNC,
tracing_read_pipe() and tracing_buffers_read() without trace_types_lock.
Two readers can both pass the LAST_BOOT test and free module_delta
twice, and a module notifier can update module_delta while it is being
freed.

Take trace_types_lock in those paths and keep the callers that already
hold it on an unlocked variant.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_