# CVE-2021-28041: Use after free in n/a

> A double free vulnerability in OpenSSH ssh-agent allows attackers to cause denial of service or execute code under specific legacy or forwarded agent conditions.

- **Severity:** High 7.1 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 5 Mar 2021
- **Updated:** 14 Oct 2026
- **Also known as:** ALPINE-CVE-2021-28041, DEBIAN-CVE-2021-28041, GHSA-gp5m-rxrx-pfrj, JLSEC-2026-64, MGASA-2021-0261, OESA-2021-1466, OESA-2022-2083, SUSE-SU-2021:4153-1, UBUNTU-CVE-2021-28041, USN-4762-1, openSUSE-SU-2021:4153-1

## What is CVE-2021-28041?

CVE-2021-28041 is a high-severity use after free vulnerability in Fedoraproject Fedora, published on 5 Mar 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

ssh-agent in OpenSSH before 8.5 has a double free that may be relevant in a few less-common scenarios, such as unconstrained agent-socket access on a legacy operating system, or the forwarding of an agent to an attacker-controlled host.

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2021-28041?

It affects 9 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `openssh` | SUSE:Linux Enterprise Micro 5.1 | All versions | 8.4p1-3.9.1 |
| `openssh` | SUSE:Linux Enterprise Module for Basesystem 15 SP3 | All versions | 8.4p1-3.9.1 |
| `openssh-askpass-gnome` | SUSE:Linux Enterprise Module for Desktop Applications 15 SP3 | All versions | 8.4p1-3.9.1 |
| `openssh` | SUSE:Linux Enterprise Module for Server Applications 15 SP3 | All versions | 8.4p1-3.9.1 |
| `openssh` | openSUSE:Leap 15.3 | All versions | 8.4p1-3.9.1 |
| `openssh-askpass-gnome` | openSUSE:Leap 15.3 | All versions | 8.4p1-3.9.1 |

Products: Fedoraproject Fedora, Netapp Cloud Backup, Netapp Hci Compute Node Firmware, Netapp Hci Management Node, Netapp Hci Storage Node Firmware, Netapp Solidfire, OpenSSH, Oracle Communications Offline Mediation Controller, Oracle Zfs Storage Appliance.

## How do I fix CVE-2021-28041?

Upgrade to a fixed version.

## Is CVE-2021-28041 being exploited?

There is no known exploitation of CVE-2021-28041 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28041 and fix it if it is affected.

What it is: CVE-2021-28041 is a high-severity use after free vulnerability in Fedoraproject Fedora, published on 5 Mar 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-28041 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2021-28041/ (Markdown: https://insights.sbomify.com/CVE-2021-28041/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28041
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28041
- OSV: https://osv.dev/vulnerability/CVE-2021-28041

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28041/
Summaries are generated and may contain mistakes; the official description above is the record.