# CVE-2023-52609: binder: fix race between mmput() and do_exit()

> A race condition in the Linux kernel binder driver can cause a denial of service by blocking cleanup tasks when a process exits unexpectedly.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/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:** 18 Mar 2024
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-52609, DEBIAN-CVE-2023-52609, GHSA-5h3h-5652-8xp5, UBUNTU-CVE-2023-52609

## What is CVE-2023-52609?

CVE-2023-52609 is a medium-severity vulnerability in Debian Debian Linux, published on 18 Mar 2024. 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:

binder: fix race between mmput() and do_exit()

Task A calls binder_update_page_range() to allocate and insert pages on
a remote address space from Task B. For this, Task A pins the remote mm
via mmget_not_zero() first. This can race with Task B do_exit() and the
final mmput() refcount decrement will come from Task A.

  Task A            | Task B
  ------------------+------------------
  mmget_not_zero()  |
                    |  do_exit()
                    |    exit_mm()
                    |      mmput()
  mmput()           |
    exit_mmap()     |
      remove_vma()  |
        fput()      |

In this case, the work of ____fput() from Task B is queued up in Task A
as TWA_RESUME. So in theory, Task A returns to userspace and the cleanup
work gets executed. However, Task A instead sleep, waiting for a reply
from Task B that never comes (it's dead).

This means the binder_deferred_release() is blocked until an unrelated
binder event forces Task A to go back to userspace. All the associated
death notifications will also be delayed until then.

In order to fix this use mmput_async() that will schedule the work in
the corresponding mm->async_put_work WQ instead of Task A.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2023-52609?

It affects 2 products.


Products: Debian Debian Linux, Linux kernel.

## How do I fix CVE-2023-52609?

Apply the vendor's patch.

## Is CVE-2023-52609 being exploited?

There is no known exploitation of CVE-2023-52609 in the wild and no public exploit code.

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## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-52609 and fix it if it is affected.

What it is: CVE-2023-52609 is a medium-severity vulnerability in Debian Debian Linux, published on 18 Mar 2024. 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-2023-52609 in the wild and no public exploit code.

Affected product: Debian Debian 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-2023-52609/ (Markdown: https://insights.sbomify.com/CVE-2023-52609/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-52609
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-52609
- OSV: https://osv.dev/vulnerability/CVE-2023-52609

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-52609/
Summaries are generated and may contain mistakes; the official description above is the record.