# CVE-2026-46173: exit: prevent preemption of oopsing TASK_DEAD task

> A race condition in Linux kernel task exit handling allows use-after-free of task stacks, potentially leading to memory corruption and privilege escalation.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-89031, BELL-CVE-2026-46173, DEBIAN-CVE-2026-46173, GHSA-mpr4-2mm3-rwm6, ROOT-OS-DEBIAN-12-CVE-2026-46173, ROOT-OS-UBUNTU-2404-CVE-2026-46173, UBUNTU-CVE-2026-46173

## What is CVE-2026-46173?

CVE-2026-46173 is a high-severity use after free vulnerability in Linux kernel, published on 28 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

exit: prevent preemption of oopsing TASK_DEAD task

When an already-exiting task oopses, make_task_dead() currently calls
do_task_dead() with preemption enabled.  That is forbidden:
do_task_dead() calls __schedule(), which has a comment saying "WARNING:
must be called with preemption disabled!".

If an oopsing task is preempted in do_task_dead(), between becoming
TASK_DEAD and entering the scheduler explicitly, bad things happen:
finish_task_switch() assumes that once the scheduler has switched away
from a TASK_DEAD task, the task can never run again and its stack is no
longer needed; but that assumption apparently doesn't hold if the dead
task was preempted (the SM_PREEMPT case).

This means that the scheduler ends up repeatedly dropping references on
the dead task's stack, which can lead to use-after-free or double-free
of the entire task stack; in other words, two tasks can end up running
on the same stack, resulting in various kinds of memory corruption.

(This does not just affect "recursively oopsing" tasks; it is enough to
oops once during task exit, for example in a file_operations::release
handler)

Weakness: CWE-787 (Out-of-bounds Write), CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-46173?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46173?

Apply the vendor's patch.

## Is CVE-2026-46173 being exploited?

There is no known exploitation of CVE-2026-46173 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46173 and fix it if it is affected.

What it is: CVE-2026-46173 is a high-severity use after free vulnerability in Linux kernel, published on 28 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-46173 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-46173/ (Markdown: https://insights.sbomify.com/CVE-2026-46173/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46173
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46173
- OSV: https://osv.dev/vulnerability/CVE-2026-46173

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46173/
Summaries are generated and may contain mistakes; the official description above is the record.