# CVE-2021-47265: RDMA: Verify port when creating flow rule

> A missing port validation in the Linux kernel RDMA driver allows local attackers to trigger a null pointer dereference, causing a system crash.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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:** 21 May 2024
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2021-47265, GHSA-mjhg-c85c-62fv, ROOT-OS-DEBIAN-11-CVE-2021-47265, UBUNTU-CVE-2021-47265

## What is CVE-2021-47265?

CVE-2021-47265 is a medium-severity vulnerability in Linux kernel, published on 21 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:

RDMA: Verify port when creating flow rule

Validate port value provided by the user and with that remove no longer
needed validation by the driver.  The missing check in the mlx5_ib driver
could cause to the below oops.

Call trace:
  _create_flow_rule+0x2d4/0xf28 [mlx5_ib]
  mlx5_ib_create_flow+0x2d0/0x5b0 [mlx5_ib]
  ib_uverbs_ex_create_flow+0x4cc/0x624 [ib_uverbs]
  ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE+0xd4/0x150 [ib_uverbs]
  ib_uverbs_cmd_verbs.isra.7+0xb28/0xc50 [ib_uverbs]
  ib_uverbs_ioctl+0x158/0x1d0 [ib_uverbs]
  do_vfs_ioctl+0xd0/0xaf0
  ksys_ioctl+0x84/0xb4
  __arm64_sys_ioctl+0x28/0xc4
  el0_svc_common.constprop.3+0xa4/0x254
  el0_svc_handler+0x84/0xa0
  el0_svc+0x10/0x26c
 Code: b9401260 f9615681 51000400 8b001c20 (f9403c1a)

## Which versions are affected by CVE-2021-47265?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47265?

Apply the vendor's patch.

## Is CVE-2021-47265 being exploited?

There is no known exploitation of CVE-2021-47265 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-2021-47265 and fix it if it is affected.

What it is: CVE-2021-47265 is a medium-severity vulnerability in Linux kernel, published on 21 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-2021-47265 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-2021-47265/ (Markdown: https://insights.sbomify.com/CVE-2021-47265/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47265
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47265
- OSV: https://osv.dev/vulnerability/CVE-2021-47265

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47265/
Summaries are generated and may contain mistakes; the official description above is the record.