# CVE-2020-27786: Use after free in kernel

> A local attacker with MIDI device permissions can trigger a use-after-free in the Linux kernel, potentially leading to privilege escalation or code execution.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/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:** 11 Dec 2020
- **Updated:** 4 Aug 2024
- **Also known as:** A-175769013, DEBIAN-CVE-2020-27786, GHSA-3mfq-6299-p3w3, PUB-A-175769013, UBUNTU-CVE-2020-27786

## What is CVE-2020-27786?

CVE-2020-27786 is a high-severity use after free vulnerability in Linux kernel, published on 11 Dec 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A flaw was found in the Linux kernel’s implementation of MIDI, where an attacker with a local account and the permissions to issue ioctl commands to midi devices could trigger a use-after-free issue. A write to this specific memory while freed and before use causes the flow of execution to change and possibly allow for memory corruption or privilege escalation. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2020-27786?

It affects 6 products.


Products: Linux kernel, Netapp Cloud Backup, Netapp Solidfire Baseboard Management Controller, Redhat Enterprise Linux, Redhat Enterprise Mrg, Redhat Openshift Container Platform.

## How do I fix CVE-2020-27786?

Apply the vendor's patch.

## Is CVE-2020-27786 being exploited?

There is no known exploitation of CVE-2020-27786 in the wild and no public exploit code.

Public exploit code:

- 4.9 Kernel Exploit for CVE-2020-27786 (github_poc): https://github.com/kiks7/CVE-2020-27786-Kernel-Exploit
- https://github.com/ii4gsp/CVE-2020-27786 (github_poc): https://github.com/ii4gsp/CVE-2020-27786
- https://github.com/elbiazo/CVE-2020-27786 (github_poc): https://github.com/elbiazo/CVE-2020-27786
- https://github.com/Trinadh465/linux-4.19.72_CVE-2020-27786 (github_poc): https://github.com/Trinadh465/linux-4.19.72_CVE-2020-27786

## 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-2020-27786 and fix it if it is affected.

What it is: CVE-2020-27786 is a high-severity use after free vulnerability in Linux kernel, published on 11 Dec 2020. 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-2020-27786 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-2020-27786/ (Markdown: https://insights.sbomify.com/CVE-2020-27786/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-27786
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-27786
- OSV: https://osv.dev/vulnerability/CVE-2020-27786

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-27786/
Summaries are generated and may contain mistakes; the official description above is the record.