# CVE-2026-53230: net/mlx5: Fix slab-out-of-bounds in mlx5_query_nic_vport_mac_list

> A slab-out-of-bounds write in the mlx5 driver allows attackers to cause denial of service or potentially execute code via crafted firmware responses.

- **Severity:** High 8.7 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:L/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 Jun 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-90882, BELL-CVE-2026-53230, DEBIAN-CVE-2026-53230, GHSA-pw9r-h2m6-6vvg, ROOT-OS-DEBIAN-11-CVE-2026-53230, ROOT-OS-DEBIAN-12-CVE-2026-53230, ROOT-OS-UBUNTU-2204-CVE-2026-53230, ROOT-OS-UBUNTU-2404-CVE-2026-53230, UBUNTU-CVE-2026-53230

## What is CVE-2026-53230?

CVE-2026-53230 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Jun 2026. 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/mlx5: Fix slab-out-of-bounds in mlx5_query_nic_vport_mac_list

mlx5_query_nic_vport_mac_list() sizes its firmware command buffer using
the PF's log_max_current_uc/mc_list capabilities. When querying a VF
vport with a larger configured max (via devlink), the firmware response
can overflow this buffer:

 BUG: KASAN: slab-out-of-bounds in mlx5_query_nic_vport_mac_list+0x453/0x4c0 [mlx5_core]
 Read of size 4 at addr ff1100013ffc8a12 by task kworker/u96:2/385

 CPU: 12 UID: 0 PID: 385 Comm: kworker/u96:2 Not tainted 7.0.0-rc6+ #1 PREEMPT
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009)
 Workqueue: mlx5_esw_wq esw_vport_change_handler [mlx5_core]
 Call Trace:
  <TASK>
  dump_stack_lvl+0x69/0xa0
  print_report+0x176/0x4e4
  kasan_report+0xc8/0x100
  mlx5_query_nic_vport_mac_list+0x453/0x4c0 [mlx5_core]
  esw_update_vport_addr_list+0x2e3/0xda0 [mlx5_core]
  esw_vport_change_handle_locked+0xa1f/0x1060 [mlx5_core]
  esw_vport_change_handler+0x6a/0x90 [mlx5_core]
  process_one_work+0x87f/0x15e0
  worker_thread+0x62b/0x1020
  kthread+0x375/0x490
  ret_from_fork+0x4dc/0x810
  ret_from_fork_asm+0x11/0x20
  </TASK>

Fix by querying the vport's own HCA caps to size the buffer correctly.
Refactor the function to allocate and return the MAC list internally,
removing the caller's dependency on knowing the correct max.

Weakness: CWE-125 (Out-of-bounds Read), CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-53230?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53230?

Apply the vendor's patch.

## Is CVE-2026-53230 being exploited?

There is no known exploitation of CVE-2026-53230 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-2026-53230 and fix it if it is affected.

What it is: CVE-2026-53230 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Jun 2026. 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-2026-53230 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-2026-53230/ (Markdown: https://insights.sbomify.com/CVE-2026-53230/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53230
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53230
- OSV: https://osv.dev/vulnerability/CVE-2026-53230

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53230/
Summaries are generated and may contain mistakes; the official description above is the record.