# CVE-2026-89545: sunrpc: defer rq_argp and rq_resp free until after RCU grace period

> A use-after-free in the Linux kernel's sunrpc module allows attackers to potentially execute code or escalate privileges via race conditions in RCU handling.

- **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:** 11 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-100280, BELL-CVE-2026-89545, DEBIAN-CVE-2026-89545, GHSA-43p7-fx92-rp4x, UBUNTU-CVE-2026-89545

## What is CVE-2026-89545?

CVE-2026-89545 is a high-severity use after free vulnerability in Linux, published on 11 Sep 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:

sunrpc: defer rq_argp and rq_resp free until after RCU grace period

svc_rqst_free() frees rqstp->rq_argp and rqstp->rq_resp synchronously
via kfree(), but defers the rqstp struct free via kfree_rcu().  After
svc_exit_thread() calls list_del_rcu() and svc_rqst_free(), there is
a window where RCU readers that started before list_del_rcu() can still
traverse the thread list and find the rqstp.  These readers (e.g.
nfsd_nl_rpc_status_get_dumpit()) dereference rqstp->rq_argp, which has
already been freed — a use-after-free.

Fix this by moving the kfree of rq_argp and rq_resp into an explicit
call_rcu() callback alongside the struct free.  Resources not accessed
by RCU readers (bvec, buffer pages, scratch folio, auth_data) remain
synchronously freed.

## Which versions are affected by CVE-2026-89545?


## How do I fix CVE-2026-89545?

Apply the vendor's patch.

## Is CVE-2026-89545 being exploited?

There is no known exploitation of CVE-2026-89545 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89545 and fix it if it is affected.

What it is: CVE-2026-89545 is a high-severity use after free vulnerability in Linux, published on 11 Sep 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-2026-89545 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-2026-89545/ (Markdown: https://insights.sbomify.com/CVE-2026-89545/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89545
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89545
- OSV: https://osv.dev/vulnerability/CVE-2026-89545

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89545/
Summaries are generated and may contain mistakes; the official description above is the record.