# CVE-2010-2023: Race condition in n/a

> Local attackers can exploit a race condition in Exim's appendfile transport to gain privileges or cause denial of service when using world-writable sticky-bit mail directories.

- **Severity:** Medium 4.4 (`AV:L/AC:M/Au:N/C:P/I:P/A:P`)
- **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:** 7 Jun 2010
- **Updated:** 7 Aug 2024
- **Also known as:** DEBIAN-CVE-2010-2023, GHSA-qrcj-mq48-333m

## What is CVE-2010-2023?

CVE-2010-2023 is a medium-severity vulnerability in Exim Exim, published on 7 Jun 2010. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

transports/appendfile.c in Exim before 4.72, when a world-writable sticky-bit mail directory is used, does not verify the st_nlink field of mailbox files, which allows local users to cause a denial of service or possibly gain privileges by creating a hard link to another user's file.

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

## Which versions are affected by CVE-2010-2023?

It affects 1 product.


Products: Exim Exim.

## How do I fix CVE-2010-2023?

Upgrade to a fixed version.

## Is CVE-2010-2023 being exploited?

There is no known exploitation of CVE-2010-2023 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-2010-2023 and fix it if it is affected.

What it is: CVE-2010-2023 is a medium-severity vulnerability in Exim Exim, published on 7 Jun 2010. 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-2010-2023 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-2010-2023/ (Markdown: https://insights.sbomify.com/CVE-2010-2023/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2010-2023
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2010-2023
- OSV: https://osv.dev/vulnerability/CVE-2010-2023

---
From sbomify Insights: https://insights.sbomify.com/CVE-2010-2023/
Summaries are generated and may contain mistakes; the official description above is the record.