# CVE-2023-53855: net: dsa: ocelot: call dsa_tag_8021q_unregister() under rtnl_lock() on driver remove

> A race condition in the Linux kernel Ocelot DSA driver causes a kernel warning and potential instability when unbinding the driver under specific conditions.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-53855, DEBIAN-CVE-2023-53855, GHSA-c8r8-vrhj-v7vp, ROOT-OS-UBUNTU-2204-CVE-2023-53855, UBUNTU-CVE-2023-53855

## What is CVE-2023-53855?

CVE-2023-53855 is a vulnerability in Linux, published on 9 Dec 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: dsa: ocelot: call dsa_tag_8021q_unregister() under rtnl_lock() on driver remove

When the tagging protocol in current use is "ocelot-8021q" and we unbind
the driver, we see this splat:

$ echo '0000:00:00.2' > /sys/bus/pci/drivers/fsl_enetc/unbind
mscc_felix 0000:00:00.5 swp0: left promiscuous mode
sja1105 spi2.0: Link is Down
DSA: tree 1 torn down
mscc_felix 0000:00:00.5 swp2: left promiscuous mode
sja1105 spi2.2: Link is Down
DSA: tree 3 torn down
fsl_enetc 0000:00:00.2 eno2: left promiscuous mode
mscc_felix 0000:00:00.5: Link is Down
------------[ cut here ]------------
RTNL: assertion failed at net/dsa/tag_8021q.c (409)
WARNING: CPU: 1 PID: 329 at net/dsa/tag_8021q.c:409 dsa_tag_8021q_unregister+0x12c/0x1a0
Modules linked in:
CPU: 1 PID: 329 Comm: bash Not tainted 6.5.0-rc3+ #771
pc : dsa_tag_8021q_unregister+0x12c/0x1a0
lr : dsa_tag_8021q_unregister+0x12c/0x1a0
Call trace:
 dsa_tag_8021q_unregister+0x12c/0x1a0
 felix_tag_8021q_teardown+0x130/0x150
 felix_teardown+0x3c/0xd8
 dsa_tree_teardown_switches+0xbc/0xe0
 dsa_unregister_switch+0x168/0x260
 felix_pci_remove+0x30/0x60
 pci_device_remove+0x4c/0x100
 device_release_driver_internal+0x188/0x288
 device_links_unbind_consumers+0xfc/0x138
 device_release_driver_internal+0xe0/0x288
 device_driver_detach+0x24/0x38
 unbind_store+0xd8/0x108
 drv_attr_store+0x30/0x50
---[ end trace 0000000000000000 ]---
------------[ cut here ]------------
RTNL: assertion failed at net/8021q/vlan_core.c (376)
WARNING: CPU: 1 PID: 329 at net/8021q/vlan_core.c:376 vlan_vid_del+0x1b8/0x1f0
CPU: 1 PID: 329 Comm: bash Tainted: G        W          6.5.0-rc3+ #771
pc : vlan_vid_del+0x1b8/0x1f0
lr : vlan_vid_del+0x1b8/0x1f0
 dsa_tag_8021q_unregister+0x8c/0x1a0
 felix_tag_8021q_teardown+0x130/0x150
 felix_teardown+0x3c/0xd8
 dsa_tree_teardown_switches+0xbc/0xe0
 dsa_unregister_switch+0x168/0x260
 felix_pci_remove+0x30/0x60
 pci_device_remove+0x4c/0x100
 device_release_driver_internal+0x188/0x288
 device_links_unbind_consumers+0xfc/0x138
 device_release_driver_internal+0xe0/0x288
 device_driver_detach+0x24/0x38
 unbind_store+0xd8/0x108
 drv_attr_store+0x30/0x50
DSA: tree 0 torn down

This was somewhat not so easy to spot, because "ocelot-8021q" is not the
default tagging protocol, and thus, not everyone who tests the unbinding
path may have switched to it beforehand. The default
felix_tag_npi_teardown() does not require rtnl_lock() to be held.

## Which versions are affected by CVE-2023-53855?


## How do I fix CVE-2023-53855?

Apply the vendor's patch.

## Is CVE-2023-53855 being exploited?

There is no known exploitation of CVE-2023-53855 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-53855 and fix it if it is affected.

What it is: CVE-2023-53855 is a vulnerability in Linux, published on 9 Dec 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-2023-53855 in the wild and no public exploit code.

Affected product: 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-2023-53855/ (Markdown: https://insights.sbomify.com/CVE-2023-53855/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53855
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53855
- OSV: https://osv.dev/vulnerability/CVE-2023-53855

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53855/
Summaries are generated and may contain mistakes; the official description above is the record.