# CVE-2026-22980: nfsd: provide locking for v4_end_grace

> A race condition in the Linux kernel NFS server allows a use-after-free vulnerability, potentially leading to code execution or denial of service.

- **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:** 23 Jan 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-78458, BELL-CVE-2026-22980, DEBIAN-CVE-2026-22980, GHSA-334x-45wh-5m94, ROOT-OS-DEBIAN-11-CVE-2026-22980, ROOT-OS-DEBIAN-12-CVE-2026-22980, ROOT-OS-DEBIAN-13-CVE-2026-22980, ROOT-OS-UBUNTU-2204-CVE-2026-22980, ROOT-OS-UBUNTU-2404-CVE-2026-22980, UBUNTU-CVE-2026-22980

## What is CVE-2026-22980?

CVE-2026-22980 is a high-severity use after free vulnerability in Linux kernel, published on 23 Jan 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:

nfsd: provide locking for v4_end_grace

Writing to v4_end_grace can race with server shutdown and result in
memory being accessed after it was freed - reclaim_str_hashtbl in
particularly.

We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is
held while client_tracking_op->init() is called and that can wait for
an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a
deadlock.

nfsd4_end_grace() is also called by the landromat work queue and this
doesn't require locking as server shutdown will stop the work and wait
for it before freeing anything that nfsd4_end_grace() might access.

However, we must be sure that writing to v4_end_grace doesn't restart
the work item after shutdown has already waited for it.  For this we
add a new flag protected with nn->client_lock.  It is set only while it
is safe to make client tracking calls, and v4_end_grace only schedules
work while the flag is set with the spinlock held.

So this patch adds a nfsd_net field "client_tracking_active" which is
set as described.  Another field "grace_end_forced", is set when
v4_end_grace is written.  After this is set, and providing
client_tracking_active is set, the laundromat is scheduled.
This "grace_end_forced" field bypasses other checks for whether the
grace period has finished.

This resolves a race which can result in use-after-free.

Weakness: CWE-416 (Use After Free), CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-22980?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-22980?

Apply the vendor's patch.

## Is CVE-2026-22980 being exploited?

There is no known exploitation of CVE-2026-22980 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-2026-22980 and fix it if it is affected.

What it is: CVE-2026-22980 is a high-severity use after free vulnerability in Linux kernel, published on 23 Jan 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-2026-22980 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-2026-22980/ (Markdown: https://insights.sbomify.com/CVE-2026-22980/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-22980
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-22980
- OSV: https://osv.dev/vulnerability/CVE-2026-22980

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-22980/
Summaries are generated and may contain mistakes; the official description above is the record.