# CVE-2021-47438: net/mlx5e: Fix memory leak in mlx5_core_destroy_cq() error path

> A memory leak in the Linux kernel's mlx5 network driver allows attackers to cause a denial of service by exhausting system memory.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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:** 22 May 2024
- **Updated:** 5 Aug 2026
- **Also known as:** DEBIAN-CVE-2021-47438, GHSA-24vw-fq64-647q, UBUNTU-CVE-2021-47438

## What is CVE-2021-47438?

CVE-2021-47438 is a high-severity memory corruption vulnerability in Linux kernel, published on 22 May 2024. 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/mlx5e: Fix memory leak in mlx5_core_destroy_cq() error path

Prior to this patch in case mlx5_core_destroy_cq() failed it returns
without completing all destroy operations and that leads to memory leak.
Instead, complete the destroy flow before return error.

Also move mlx5_debug_cq_remove() to the beginning of mlx5_core_destroy_cq()
to be symmetrical with mlx5_core_create_cq().

kmemleak complains on:

unreferenced object 0xc000000038625100 (size 64):
  comm "ethtool", pid 28301, jiffies 4298062946 (age 785.380s)
  hex dump (first 32 bytes):
    60 01 48 94 00 00 00 c0 b8 05 34 c3 00 00 00 c0  `.H.......4.....
    02 00 00 00 00 00 00 00 00 db 7d c1 00 00 00 c0  ..........}.....
  backtrace:
    [<000000009e8643cb>] add_res_tree+0xd0/0x270 [mlx5_core]
    [<00000000e7cb8e6c>] mlx5_debug_cq_add+0x5c/0xc0 [mlx5_core]
    [<000000002a12918f>] mlx5_core_create_cq+0x1d0/0x2d0 [mlx5_core]
    [<00000000cef0a696>] mlx5e_create_cq+0x210/0x3f0 [mlx5_core]
    [<000000009c642c26>] mlx5e_open_cq+0xb4/0x130 [mlx5_core]
    [<0000000058dfa578>] mlx5e_ptp_open+0x7f4/0xe10 [mlx5_core]
    [<0000000081839561>] mlx5e_open_channels+0x9cc/0x13e0 [mlx5_core]
    [<0000000009cf05d4>] mlx5e_switch_priv_channels+0xa4/0x230
[mlx5_core]
    [<0000000042bbedd8>] mlx5e_safe_switch_params+0x14c/0x300
[mlx5_core]
    [<0000000004bc9db8>] set_pflag_tx_port_ts+0x9c/0x160 [mlx5_core]
    [<00000000a0553443>] mlx5e_set_priv_flags+0xd0/0x1b0 [mlx5_core]
    [<00000000a8f3d84b>] ethnl_set_privflags+0x234/0x2d0
    [<00000000fd27f27c>] genl_family_rcv_msg_doit+0x108/0x1d0
    [<00000000f495e2bb>] genl_family_rcv_msg+0xe4/0x1f0
    [<00000000646c5c2c>] genl_rcv_msg+0x78/0x120
    [<00000000d53e384e>] netlink_rcv_skb+0x74/0x1a0

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2021-47438?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47438?

Apply the vendor's patch.

## Is CVE-2021-47438 being exploited?

There is no known exploitation of CVE-2021-47438 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-2021-47438 and fix it if it is affected.

What it is: CVE-2021-47438 is a high-severity memory corruption vulnerability in Linux kernel, published on 22 May 2024. 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-2021-47438 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-2021-47438/ (Markdown: https://insights.sbomify.com/CVE-2021-47438/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47438
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47438
- OSV: https://osv.dev/vulnerability/CVE-2021-47438

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47438/
Summaries are generated and may contain mistakes; the official description above is the record.