# CVE-2021-26708: Race condition in n/a

> A local attacker can exploit race conditions in the Linux kernel's AF_VSOCK implementation to escalate privileges.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/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:** 5 Feb 2021
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-26708, GHSA-hhxw-8c9w-q5q9, MGASA-2021-0084, UBUNTU-CVE-2021-26708, USN-4727-1

## What is CVE-2021-26708?

CVE-2021-26708 is a high-severity vulnerability in Linux kernel, published on 5 Feb 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A local privilege escalation was discovered in the Linux kernel before 5.10.13. Multiple race conditions in the AF_VSOCK implementation are caused by wrong locking in net/vmw_vsock/af_vsock.c. The race conditions were implicitly introduced in the commits that added VSOCK multi-transport support.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2021-26708?

It affects 9 products.


Products: Linux kernel, Netapp Aff Baseboard Management Controller, Netapp Baseboard Management Controller 500f Firmware, Netapp Baseboard Management Controller A250 Firmware, Netapp Cloud Backup, Netapp Fas Baseboard Management Controller, Netapp Hci H410c Firmware, Netapp Solidfire \& Hci Management Node, Netapp Solidfire Baseboard Management Controller.

## How do I fix CVE-2021-26708?

Apply the vendor's patch.

## Is CVE-2021-26708 being exploited?

There is no known exploitation of CVE-2021-26708 in the wild and no public exploit code.

Public exploit code:

- Investigating the bug behind CVE-2021-26708 (github_poc): https://github.com/jordan9001/vsock_poc
- Automated reproduction and analysis of CVE-2021-26708 — a use-after-free vulnerability in the Linux kernel's AF_VSOCK subsystem (v5.10.12). Includes PoC exploit code, KASAN runtime detection report, and the full kernel build configuration for environment replication. Built with KernJC. (github_poc): https://github.com/kungaocode/vulnerability-analysis-
- https://github.com/azpema/CVE-2021-26708 (github_poc): https://github.com/azpema/CVE-2021-26708

## 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-2021-26708 and fix it if it is affected.

What it is: CVE-2021-26708 is a high-severity vulnerability in Linux kernel, published on 5 Feb 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-2021-26708 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-2021-26708/ (Markdown: https://insights.sbomify.com/CVE-2021-26708/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-26708
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-26708
- OSV: https://osv.dev/vulnerability/CVE-2021-26708

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-26708/
Summaries are generated and may contain mistakes; the official description above is the record.