# CVE-2020-27777: Privilege escalation in kernel

> A local root user on PowerVM or KVM pseries systems with Secure Boot can escalate privileges to kernel level due to improper RTAS memory access handling.

- **Severity:** Medium 6.7 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Dec 2020
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2020-27777, GHSA-w5hm-w8cx-wrwr, UBUNTU-CVE-2020-27777

## What is CVE-2020-27777?

CVE-2020-27777 is a medium-severity vulnerability in Linux kernel, published on 15 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 way RTAS handled memory accesses in userspace to kernel communication. On a locked down (usually due to Secure Boot) guest system running on top of PowerVM or KVM hypervisors (pseries platform) a root like local user could use this flaw to further increase their privileges to that of a running kernel.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2020-27777?

It affects 3 products.


Products: Linux kernel, Redhat Enterprise Linux, Redhat Openshift Container Platform.

## How do I fix CVE-2020-27777?

Apply the vendor's patch.

## Is CVE-2020-27777 being exploited?

There is no known exploitation of CVE-2020-27777 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-2020-27777 and fix it if it is affected.

What it is: CVE-2020-27777 is a medium-severity vulnerability in Linux kernel, published on 15 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-2020-27777 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-2020-27777/ (Markdown: https://insights.sbomify.com/CVE-2020-27777/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-27777
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-27777
- OSV: https://osv.dev/vulnerability/CVE-2020-27777

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-27777/
Summaries are generated and may contain mistakes; the official description above is the record.