# CVE-2022-3559: Exim Regex use after free

> A use-after-free vulnerability in Exim's regex handler allows attackers to potentially execute arbitrary code or cause a denial of service.

- **Severity:** Medium 4.6 (`CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L`)
- **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:** 17 Oct 2022
- **Updated:** 3 Nov 2025
- **Also known as:** CLSA-2023-1699908139, CLSA-2023-1699908687, DEBIAN-CVE-2022-3559, GHSA-86wj-xg3c-r8gx, UBUNTU-CVE-2022-3559, USN-5741-1, openSUSE-SU-2022:10168-1, openSUSE-SU-2022:10191-1, openSUSE-SU-2024:12422-1

## What is CVE-2022-3559?

CVE-2022-3559 is a medium-severity use after free vulnerability in Exim Exim, published on 17 Oct 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability was found in Exim and classified as problematic. This issue affects some unknown processing of the component Regex Handler. The manipulation leads to use after free. The name of the patch is 4e9ed49f8f12eb331b29bd5b6dc3693c520fddc2. It is recommended to apply a patch to fix this issue. The identifier VDB-211073 was assigned to this vulnerability.

Weakness: CWE-416 (Use After Free), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2022-3559?

It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `exim` | SUSE:Package Hub 15 SP3 | All versions | 4.94.2-bp153.5.1 |
| `exim` | SUSE:Package Hub 15 SP4 | All versions | 4.94.2-bp154.2.3.1 |
| `exim` | openSUSE:Leap 15.3 | All versions | 4.94.2-bp153.5.1 |
| `exim` | openSUSE:Leap 15.4 | All versions | 4.94.2-bp154.2.3.1 |
| `exim` | openSUSE:Tumbleweed | All versions | 4.96-3.1 |

Products: Exim Exim, Fedoraproject Fedora.

## How do I fix CVE-2022-3559?

Apply the vendor's patch.

## Is CVE-2022-3559 being exploited?

There is no known exploitation of CVE-2022-3559 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-2022-3559 and fix it if it is affected.

What it is: CVE-2022-3559 is a medium-severity use after free vulnerability in Exim Exim, published on 17 Oct 2022. 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-2022-3559 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-2022-3559/ (Markdown: https://insights.sbomify.com/CVE-2022-3559/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-3559
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-3559
- OSV: https://osv.dev/vulnerability/CVE-2022-3559

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-3559/
Summaries are generated and may contain mistakes; the official description above is the record.