# CVE-2020-25668: Use after free in Linux Kernel

> A use-after-free flaw in the Linux Kernel console driver allows local attackers to execute arbitrary code or 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:** 26 May 2021
- **Updated:** 4 Aug 2024
- **Also known as:** A-190228658, DEBIAN-CVE-2020-25668, PUB-A-190228658, SUSE-SU-2020:3698-1, UBUNTU-CVE-2020-25668

## What is CVE-2020-25668?

CVE-2020-25668 is a high-severity use after free vulnerability in Debian Debian Linux, published on 26 May 2021. 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 Linux Kernel because access to the global variable fg_console is not properly synchronized leading to a use after free in con_font_op.

Weakness: CWE-662 (Improper Synchronization), CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2020-25668?

It affects 15 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kgraft-patch-SLE12-SP5_Update_12` | SUSE:Linux Enterprise Live Patching 12 SP5 | All versions | 2-2.1 |
| `kernel-livepatch-SLE15-SP2_Update_7` | SUSE:Linux Enterprise Live Patching 15 SP2 | All versions | 2-2.1 |

Products: Debian Debian Linux, Linux kernel, Netapp 500f Firmware, Netapp A250 Firmware, Netapp Cloud Backup, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410c Firmware, Netapp H410s Firmware, Netapp H500e Firmware, Netapp H500s Firmware, Netapp H700e Firmware, Netapp H700s Firmware, Netapp Solidfire \& Hci Management Node, Netapp Solidfire Baseboard Management Controller Firmware.

## How do I fix CVE-2020-25668?

Apply the vendor's patch.

## Is CVE-2020-25668 being exploited?

There is no known exploitation of CVE-2020-25668 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-25668 and fix it if it is affected.

What it is: CVE-2020-25668 is a high-severity use after free vulnerability in Debian Debian Linux, published on 26 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-2020-25668 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2020-25668/ (Markdown: https://insights.sbomify.com/CVE-2020-25668/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-25668
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-25668
- OSV: https://osv.dev/vulnerability/CVE-2020-25668

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-25668/
Summaries are generated and may contain mistakes; the official description above is the record.