# CVE-2025-38209: nvme-tcp: remove tag set when second admin queue config fails

> A use-after-free in the Linux kernel NVMe-TCP driver allows attackers to cause a system crash or potentially execute code via crafted network traffic.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Jul 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2025-38209, GHSA-w8w5-45x4-qwqp, UBUNTU-CVE-2025-38209

## What is CVE-2025-38209?

CVE-2025-38209 is a critical use after free vulnerability in Linux kernel, published on 4 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

nvme-tcp: remove tag set when second admin queue config fails

Commit 104d0e2f6222 ("nvme-fabrics: reset admin connection for secure
concatenation") modified nvme_tcp_setup_ctrl() to call
nvme_tcp_configure_admin_queue() twice. The first call prepares for
DH-CHAP negotitation, and the second call is required for secure
concatenation. However, this change triggered BUG KASAN slab-use-after-
free in blk_mq_queue_tag_busy_iter(). This BUG can be recreated by
repeating the blktests test case nvme/063 a few times [1].

When the BUG happens, nvme_tcp_create_ctrl() fails in the call chain
below:

nvme_tcp_create_ctrl()
 nvme_tcp_alloc_ctrl() new=true             ... Alloc nvme_tcp_ctrl and admin_tag_set
 nvme_tcp_setup_ctrl() new=true
  nvme_tcp_configure_admin_queue() new=true ... Succeed
   nvme_alloc_admin_tag_set()               ... Alloc the tag set for admin_tag_set
  nvme_stop_keep_alive()
  nvme_tcp_teardown_admin_queue() remove=false
  nvme_tcp_configure_admin_queue() new=false
   nvme_tcp_alloc_admin_queue()             ... Fail, but do not call nvme_remove_admin_tag_set()
 nvme_uninit_ctrl()
 nvme_put_ctrl()                            ... Free up the nvme_tcp_ctrl and admin_tag_set

The first call of nvme_tcp_configure_admin_queue() succeeds with
new=true argument. The second call fails with new=false argument. This
second call does not call nvme_remove_admin_tag_set() on failure, due to
the new=false argument. Then the admin tag set is not removed. However,
nvme_tcp_create_ctrl() assumes that nvme_tcp_setup_ctrl() would call
nvme_remove_admin_tag_set(). Then it frees up struct nvme_tcp_ctrl which
has admin_tag_set field. Later on, the timeout handler accesses the
admin_tag_set field and causes the BUG KASAN slab-use-after-free.

To not leave the admin tag set, call nvme_remove_admin_tag_set() when
the second nvme_tcp_configure_admin_queue() call fails. Do not return
from nvme_tcp_setup_ctrl() on failure. Instead, jump to "destroy_admin"
go-to label to call nvme_tcp_teardown_admin_queue() which calls
nvme_remove_admin_tag_set().

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2025-38209?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-38209?

Apply the vendor's patch.

## Is CVE-2025-38209 being exploited?

There is no known exploitation of CVE-2025-38209 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-2025-38209 and fix it if it is affected.

What it is: CVE-2025-38209 is a critical use after free vulnerability in Linux kernel, published on 4 Jul 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-38209 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-2025-38209/ (Markdown: https://insights.sbomify.com/CVE-2025-38209/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-38209
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-38209
- OSV: https://osv.dev/vulnerability/CVE-2025-38209

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-38209/
Summaries are generated and may contain mistakes; the official description above is the record.