# CVE-2026-98543: bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir

> A race condition in Linux kernel BPF LSM hooks allows local attackers to modify file extended attributes without proper locking, potentially leading to privilege escalation.

- **Severity:** High 7.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:L/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:** 18 Oct 2026
- **Updated:** 24 Oct 2026
- **Also known as:** BELL-CVE-2026-98543, DEBIAN-CVE-2026-98543, GHSA-mhp5-jj6j-c7m7, UBUNTU-CVE-2026-98543

## What is CVE-2026-98543?

CVE-2026-98543 is a high-severity vulnerability in Linux, published on 18 Oct 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:

bpf: fs/xattr: don't assume the inode is locked in path_unlink/path_rmdir

bpf_lsm_has_d_inode_locked() makes the verifier rewrite
bpf_[set|remove]_dentry_xattr() to the _locked variants, which assume
that the caller already holds the inode's i_rwsem.  The path_unlink and
path_rmdir hooks are listed, but security_path_unlink() and
security_path_rmdir() run before vfs_unlink()/vfs_rmdir() take the
victim inode's i_rwsem, so a sleepable BPF LSM program attached to
either hook mutates the victim's xattrs without the lock held.

Drop the two path hooks from d_inode_locked_hooks so that the verifier
keeps the locking bpf_[set|remove]_dentry_xattr() variants, which take
the lock themselves.

## Which versions are affected by CVE-2026-98543?


## How do I fix CVE-2026-98543?

Apply the vendor's patch.

## Is CVE-2026-98543 being exploited?

There is no known exploitation of CVE-2026-98543 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98543 and fix it if it is affected.

What it is: CVE-2026-98543 is a high-severity vulnerability in Linux, published on 18 Oct 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-2026-98543 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-2026-98543/ (Markdown: https://insights.sbomify.com/CVE-2026-98543/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98543
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98543
- OSV: https://osv.dev/vulnerability/CVE-2026-98543

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98543/
Summaries are generated and may contain mistakes; the official description above is the record.