# CVE-2026-98982: namespace: don't let a pseudo dentry become the root of a mount


- **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
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** BELL-CVE-2026-98982, DEBIAN-CVE-2026-98982, GHSA-2rh7-4ph4-xmm5, UBUNTU-CVE-2026-98982

## What is CVE-2026-98982?

CVE-2026-98982 is a high-severity vulnerability in Linux, published on 23 Oct 2026. 

### Official description

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

namespace: don't let a pseudo dentry become the root of a mount

d_alloc_pseudo() hands out dentries for pipes, sockets and other files
that are never anyone's child or parent. They carry DCACHE_NORCU and
dentry_free() frees them right away because no lockless path walk can
ever reach them. That holds as long as such a dentry isn't the root of
a mount. But bind mounting /proc/self/fd/<fd> of such a file does
exactly that.

Most callers of alloc_file_pseudo() put their files on kernel-internal
mounts and may_copy_tree() refuses those. bpf_token_create() doesn't. It
places the token file on the bpffs mount the caller handed it and that
mount is in the caller's mount namespace so the clone goes through:

  mount --bind /proc/self/fd/<token> <file>
  open_tree(tokfd, "", AT_EMPTY_PATH | OPEN_TREE_CLONE) + move_mount()

__follow_mount_rcu() then loads ->mnt_root of that mount, reads d_seq
and d_flags of the dentry and only then checks mount_lock. The dentry
can be gone by then. The final mntput() of an unmounted parent unhooks
a child that stayed attached to it under mount_lock alone. When the
child's holder does the final put right after that the root is dput()
and freed immediately while a walker that found the mount hashed still
looks at it.

Refuse to clone a mount with a DCACHE_NORCU dentry as its root. Nothing
sensible can be done with a bind mount of a bpf token anyway.

## Which versions are affected by CVE-2026-98982?


## How do I fix CVE-2026-98982?

Upgrade to a fixed version.

## Is CVE-2026-98982 being exploited?

There is no known exploitation of CVE-2026-98982 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98982 and fix it if it is affected.

What it is: CVE-2026-98982 is a high-severity vulnerability in Linux, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-98982 in the wild and no public exploit code.

Affected product: Linux. 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-2026-98982/ (Markdown: https://insights.sbomify.com/CVE-2026-98982/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98982
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98982
- OSV: https://osv.dev/vulnerability/CVE-2026-98982

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98982/
Summaries are generated and may contain mistakes; the official description above is the record.