# CVE-2020-28011: Memory corruption in n/a

> Heap-based buffer overflow in Exim allows local attackers to escalate privileges from the exim user to root.

- **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:** 6 May 2021
- **Updated:** 4 Aug 2024
- **Also known as:** CLEANSTART-2025-DA82799, DEBIAN-CVE-2020-28011, GHSA-j622-pr6m-cmfr, UBUNTU-CVE-2020-28011

## What is CVE-2020-28011?

CVE-2020-28011 is a high-severity memory corruption vulnerability in Exim Exim, published on 6 May 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow in queue_run via two sender options: -R and -S. This may cause privilege escalation from exim to root.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2020-28011?

It affects 1 product.


Products: Exim Exim.

## How do I fix CVE-2020-28011?

Upgrade to a fixed version.

## Is CVE-2020-28011 being exploited?

There is no known exploitation of CVE-2020-28011 in the wild and no public exploit code.

## Other vulnerabilities in Exim Exim

- [CVE-2026-45185](https://insights.sbomify.com/CVE-2026-45185/): Use after free in Exim (critical 9.8)
- [CVE-2023-42115](https://insights.sbomify.com/CVE-2023-42115/): Exim AUTH Out-Of-Bounds Write Remote Code Execution Vulnerability (critical 9.8)
- [CVE-2020-28017](https://insights.sbomify.com/CVE-2020-28017/): Integer overflow in n/a (critical 9.8)
- [CVE-2020-28018](https://insights.sbomify.com/CVE-2020-28018/): Use after free in n/a (critical 9.8)
- [CVE-2020-28020](https://insights.sbomify.com/CVE-2020-28020/): Integer overflow in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-28011 and fix it if it is affected.

What it is: CVE-2020-28011 is a high-severity memory corruption vulnerability in Exim Exim, published on 6 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-2020-28011 in the wild and no public exploit code.

Affected product: Exim Exim. 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-2020-28011/ (Markdown: https://insights.sbomify.com/CVE-2020-28011/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-28011
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-28011
- OSV: https://osv.dev/vulnerability/CVE-2020-28011

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-28011/
Summaries are generated and may contain mistakes; the official description above is the record.