# CVE-2025-38453: io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU

> A use-after-free vulnerability in the Linux kernel's io_uring msg_ring component allows attackers to potentially 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:** 25 Jul 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2025-38453, DEBIAN-CVE-2025-38453, GHSA-9gq9-xvp8-xm4m, ROOT-OS-DEBIAN-13-CVE-2025-38453, UBUNTU-CVE-2025-38453

## What is CVE-2025-38453?

CVE-2025-38453 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jul 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:

io_uring/msg_ring: ensure io_kiocb freeing is deferred for RCU

syzbot reports that defer/local task_work adding via msg_ring can hit
a request that has been freed:

CPU: 1 UID: 0 PID: 19356 Comm: iou-wrk-19354 Not tainted 6.16.0-rc4-syzkaller-00108-g17bbde2e1716 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 io_req_local_work_add io_uring/io_uring.c:1184 [inline]
 __io_req_task_work_add+0x589/0x950 io_uring/io_uring.c:1252
 io_msg_remote_post io_uring/msg_ring.c:103 [inline]
 io_msg_data_remote io_uring/msg_ring.c:133 [inline]
 __io_msg_ring_data+0x820/0xaa0 io_uring/msg_ring.c:151
 io_msg_ring_data io_uring/msg_ring.c:173 [inline]
 io_msg_ring+0x134/0xa00 io_uring/msg_ring.c:314
 __io_issue_sqe+0x17e/0x4b0 io_uring/io_uring.c:1739
 io_issue_sqe+0x165/0xfd0 io_uring/io_uring.c:1762
 io_wq_submit_work+0x6e9/0xb90 io_uring/io_uring.c:1874
 io_worker_handle_work+0x7cd/0x1180 io_uring/io-wq.c:642
 io_wq_worker+0x42f/0xeb0 io_uring/io-wq.c:696
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

which is supposed to be safe with how requests are allocated. But msg
ring requests alloc and free on their own, and hence must defer freeing
to a sane time.

Add an rcu_head and use kfree_rcu() in both spots where requests are
freed. Only the one in io_msg_tw_complete() is strictly required as it
has been visible on the other ring, but use it consistently in the other
spot as well.

This should not cause any other issues outside of KASAN rightfully
complaining about it.

## Which versions are affected by CVE-2025-38453?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-38453?

Apply the vendor's patch.

## Is CVE-2025-38453 being exploited?

There is no known exploitation of CVE-2025-38453 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-2025-38453 and fix it if it is affected.

What it is: CVE-2025-38453 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jul 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-2025-38453 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-2025-38453/ (Markdown: https://insights.sbomify.com/CVE-2025-38453/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38453
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38453
- OSV: https://osv.dev/vulnerability/CVE-2025-38453

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38453/
Summaries are generated and may contain mistakes; the official description above is the record.