# CVE-2021-31440: Privilege escalation in Kernel

> Local attackers can escalate privileges and execute arbitrary code in the kernel context due to improper validation of eBPF programs.

- **Severity:** High 8.8 (`CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/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 2021
- **Updated:** 3 Aug 2024
- **Also known as:** A-189614572, DEBIAN-CVE-2021-31440, GHSA-c57j-pq55-rh2x, PUB-A-189614572, UBUNTU-CVE-2021-31440

## What is CVE-2021-31440?

CVE-2021-31440 is a high-severity vulnerability in Linux kernel, published on 21 May 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

This vulnerability allows local attackers to escalate privileges on affected installations of Linux Kernel 5.11.15. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability. The specific flaw exists within the handling of eBPF programs. The issue results from the lack of proper validation of user-supplied eBPF programs prior to executing them. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the kernel. Was ZDI-CAN-13661.

Weakness: CWE-682 (Incorrect Calculation)

## Which versions are affected by CVE-2021-31440?

It affects 10 products.


Products: Linux kernel, Netapp Cloud Backup, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410s Firmware, Netapp H500e Firmware, Netapp H500s Firmware, Netapp H700e Firmware, Netapp H700s Firmware, Netapp Solidfire Baseboard Management Controller Firmware.

## How do I fix CVE-2021-31440?

Apply the vendor's patch.

## Is CVE-2021-31440 being exploited?

There is no known exploitation of CVE-2021-31440 in the wild and no public exploit code.

Public exploit code:

- https://github.com/WhatsWrongAndWhy/CVE-2021-31440 (github_poc): https://github.com/WhatsWrongAndWhy/CVE-2021-31440

## 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-2021-31440 and fix it if it is affected.

What it is: CVE-2021-31440 is a high-severity vulnerability in Linux kernel, published on 21 May 2021. 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-2021-31440 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-2021-31440/ (Markdown: https://insights.sbomify.com/CVE-2021-31440/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-31440
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-31440
- OSV: https://osv.dev/vulnerability/CVE-2021-31440

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-31440/
Summaries are generated and may contain mistakes; the official description above is the record.