# CVE-2023-53445: net: qrtr: Fix a refcount bug in qrtr_recvmsg()

> A race condition in the Linux kernel QRTR subsystem allows a use-after-free, potentially enabling local attackers to execute code or escalate privileges.

- **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:** 18 Sep 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2023-53445, DEBIAN-CVE-2023-53445, GHSA-3w47-qc84-prwf, UBUNTU-CVE-2023-53445

## What is CVE-2023-53445?

CVE-2023-53445 is a high-severity use after free vulnerability in Linux kernel, published on 18 Sep 2025. 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:

net: qrtr: Fix a refcount bug in qrtr_recvmsg()

Syzbot reported a bug as following:

refcount_t: addition on 0; use-after-free.
...
RIP: 0010:refcount_warn_saturate+0x17c/0x1f0 lib/refcount.c:25
...
Call Trace:
 <TASK>
 __refcount_add include/linux/refcount.h:199 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 kref_get include/linux/kref.h:45 [inline]
 qrtr_node_acquire net/qrtr/af_qrtr.c:202 [inline]
 qrtr_node_lookup net/qrtr/af_qrtr.c:398 [inline]
 qrtr_send_resume_tx net/qrtr/af_qrtr.c:1003 [inline]
 qrtr_recvmsg+0x85f/0x990 net/qrtr/af_qrtr.c:1070
 sock_recvmsg_nosec net/socket.c:1017 [inline]
 sock_recvmsg+0xe2/0x160 net/socket.c:1038
 qrtr_ns_worker+0x170/0x1700 net/qrtr/ns.c:688
 process_one_work+0x991/0x15c0 kernel/workqueue.c:2390
 worker_thread+0x669/0x1090 kernel/workqueue.c:2537

It occurs in the concurrent scenario of qrtr_recvmsg() and
qrtr_endpoint_unregister() as following:

	cpu0					cpu1
qrtr_recvmsg				qrtr_endpoint_unregister
qrtr_send_resume_tx			qrtr_node_release
qrtr_node_lookup			mutex_lock(&qrtr_node_lock)
spin_lock_irqsave(&qrtr_nodes_lock, )	refcount_dec_and_test(&node->ref) [node->ref == 0]
radix_tree_lookup [node != NULL]	__qrtr_node_release
qrtr_node_acquire			spin_lock_irqsave(&qrtr_nodes_lock, )
kref_get(&node->ref) [WARNING]		...
					mutex_unlock(&qrtr_node_lock)

Use qrtr_node_lock to protect qrtr_node_lookup() implementation, this
is actually improving the protection of node reference.

## Which versions are affected by CVE-2023-53445?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53445?

Apply the vendor's patch.

## Is CVE-2023-53445 being exploited?

There is no known exploitation of CVE-2023-53445 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-2023-53445 and fix it if it is affected.

What it is: CVE-2023-53445 is a high-severity use after free vulnerability in Linux kernel, published on 18 Sep 2025. 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-2023-53445 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-2023-53445/ (Markdown: https://insights.sbomify.com/CVE-2023-53445/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53445
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53445
- OSV: https://osv.dev/vulnerability/CVE-2023-53445

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53445/
Summaries are generated and may contain mistakes; the official description above is the record.