# CVE-2026-43199: net/mlx5e: Fix "scheduling while atomic" in IPsec MAC address query

> A race condition in the Linux kernel mlx5 driver causes a scheduling while atomic bug, leading to system instability or denial of service.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:** 6 May 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-85926, BELL-CVE-2026-43199, DEBIAN-CVE-2026-43199, GHSA-cvxc-xfv3-gf64, ROOT-OS-UBUNTU-2404-CVE-2026-43199, UBUNTU-CVE-2026-43199

## What is CVE-2026-43199?

CVE-2026-43199 is a high-severity vulnerability in Linux kernel, published on 6 May 2026. 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:

net/mlx5e: Fix "scheduling while atomic" in IPsec MAC address query

Fix a "scheduling while atomic" bug in mlx5e_ipsec_init_macs() by
replacing mlx5_query_mac_address() with ether_addr_copy() to get the
local MAC address directly from netdev->dev_addr.

The issue occurs because mlx5_query_mac_address() queries the hardware
which involves mlx5_cmd_exec() that can sleep, but it is called from
the mlx5e_ipsec_handle_event workqueue which runs in atomic context.

The MAC address is already available in netdev->dev_addr, so no need
to query hardware. This avoids the sleeping call and resolves the bug.

Call trace:
  BUG: scheduling while atomic: kworker/u112:2/69344/0x00000200
  __schedule+0x7ab/0xa20
  schedule+0x1c/0xb0
  schedule_timeout+0x6e/0xf0
  __wait_for_common+0x91/0x1b0
  cmd_exec+0xa85/0xff0 [mlx5_core]
  mlx5_cmd_exec+0x1f/0x50 [mlx5_core]
  mlx5_query_nic_vport_mac_address+0x7b/0xd0 [mlx5_core]
  mlx5_query_mac_address+0x19/0x30 [mlx5_core]
  mlx5e_ipsec_init_macs+0xc1/0x720 [mlx5_core]
  mlx5e_ipsec_build_accel_xfrm_attrs+0x422/0x670 [mlx5_core]
  mlx5e_ipsec_handle_event+0x2b9/0x460 [mlx5_core]
  process_one_work+0x178/0x2e0
  worker_thread+0x2ea/0x430

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-43199?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43199?

Apply the vendor's patch.

## Is CVE-2026-43199 being exploited?

There is no known exploitation of CVE-2026-43199 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-2026-43199 and fix it if it is affected.

What it is: CVE-2026-43199 is a high-severity vulnerability in Linux kernel, published on 6 May 2026. 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-2026-43199 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-2026-43199/ (Markdown: https://insights.sbomify.com/CVE-2026-43199/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43199
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43199
- OSV: https://osv.dev/vulnerability/CVE-2026-43199

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43199/
Summaries are generated and may contain mistakes; the official description above is the record.