---
id: "CVE-2026-98995"
kind: "vulnerability"
aliases: ["CVE-2026-98995"]
title: "Linux kernel: mount reparenting leaves a dangling pointer, enabling use-after-free"
severity: "unknown"
cvss: null
epss: 0.00206
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["containers", "linux-kernel", "runtime", "self-hosted"]
not_affected_if: ["non-linux-systems"]
published_at: "2026-10-23T13:17:21+00:00"
first_seen_at: "2026-10-23T21:57:33+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98995", "first_seen_at": "2026-10-23T21:57:33+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-98995", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Linux kernel: mount reparenting leaves a dangling pointer, enabling use-after-free

In the Linux kernel's mount namespace code, moving a mount to a new parent leaves the old parent pointing at a mount that is later freed, so a later mount operation can follow the stale pointer. A local user who can trigger this could corrupt kernel memory, which may lead to privilege escalation.

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

## How to check

- unknown

## Fix

- unknown

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98995
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-98995

## From the sources

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

namespace: reset the old parent's ->overmount in mnt_change_mountpoint()

__umount_mnt() resets ->overmount of the parent when it unmounts the
mount that overmounts it. mnt_change_mountpoint() doesn't. It moves the
mount to its new parent and leaves the old one pointing at it.

For a mount that is moved beneath in attach_recursive_mnt() that doesn't
matter. The new mount has already reset ->overmount of the old parent by
the time the old top mount is moved onto it.

It matters for reparent() though. propagate_umount() moves a surviving
overmount onto the first ancestor that isn't going to be unmounted. The
mount it was taken from is unmounted immediately afterwards. If a file
descriptor keeps that unmounted mount alive ->overmount points at the
moved mount. That's a dangling pointer and UAF as the moved mount is
unmounted and freed.

do_lock_mount() follows ->overmount from the target path under
mount_lock. With a file descriptor on such a mount as the target of a
mount beneath topmost_overmount() walks into the freed mount and
do_lock_mount() takes references on whatever it finds there.

So reset ->overmount of the old parent in mnt_change_mountpoint() the
same way __umount_mnt() does. A mount's ->overmount is then always a
mount that is attached to it.

---

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