# CVE-2026-23400: rust_binder: call set_notification_done() without proc lock

> A deadlock in the Linux kernel's Rust binder implementation can cause a denial of service when specific IPC commands are used on non-looper threads.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 29 Mar 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-23400, DEBIAN-CVE-2026-23400, GHSA-pff6-g7ww-p3v3, UBUNTU-CVE-2026-23400

## What is CVE-2026-23400?

CVE-2026-23400 is a medium-severity vulnerability in Linux kernel, published on 29 Mar 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:

rust_binder: call set_notification_done() without proc lock

Consider the following sequence of events on a death listener:
1. The remote process dies and sends a BR_DEAD_BINDER message.
2. The local process invokes the BC_CLEAR_DEATH_NOTIFICATION command.
3. The local process then invokes the BC_DEAD_BINDER_DONE.
Then, the kernel will reply to the BC_DEAD_BINDER_DONE command with a
BR_CLEAR_DEATH_NOTIFICATION_DONE reply using push_work_if_looper().

However, this can result in a deadlock if the current thread is not a
looper. This is because dead_binder_done() still holds the proc lock
during set_notification_done(), which called push_work_if_looper().
Normally, push_work_if_looper() takes the thread lock, which is fine to
take under the proc lock. But if the current thread is not a looper,
then it falls back to delivering the reply to the process work queue,
which involves taking the proc lock. Since the proc lock is already
held, this is a deadlock.

Fix this by releasing the proc lock during set_notification_done(). It
was not intentional that it was held during that function to begin with.

I don't think this ever happens in Android because BC_DEAD_BINDER_DONE
is only invoked in response to BR_DEAD_BINDER messages, and the kernel
always delivers BR_DEAD_BINDER to a looper. So there's no scenario where
Android userspace will call BC_DEAD_BINDER_DONE on a non-looper thread.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2026-23400?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23400?

Apply the vendor's patch.

## Is CVE-2026-23400 being exploited?

There is no known exploitation of CVE-2026-23400 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-2026-23400 and fix it if it is affected.

What it is: CVE-2026-23400 is a medium-severity vulnerability in Linux kernel, published on 29 Mar 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-2026-23400 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-2026-23400/ (Markdown: https://insights.sbomify.com/CVE-2026-23400/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23400
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23400
- OSV: https://osv.dev/vulnerability/CVE-2026-23400

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23400/
Summaries are generated and may contain mistakes; the official description above is the record.