# CVE-2018-16872: Race condition in QEMU:

> An attacker with write access to a shared host filesystem can exploit a race condition in QEMU's MTP implementation to read arbitrary host files.

- **Severity:** Medium 5.0 (`CVSS:3.0/AV:L/AC:H/PR:H/UI:N/S:C/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 13 Dec 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-16872, GHSA-w3c5-x9c8-47hc, UBUNTU-CVE-2018-16872

## What is CVE-2018-16872?

CVE-2018-16872 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 13 Dec 2018. 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 qemu Media Transfer Protocol (MTP). The code opening files in usb_mtp_get_object and usb_mtp_get_partial_object and directories in usb_mtp_object_readdir doesn't consider that the underlying filesystem may have changed since the time lstat(2) was called in usb_mtp_object_alloc, a classical TOCTTOU problem. An attacker with write access to the host filesystem shared with a guest can use this property to navigate the host filesystem in the context of the QEMU process and read any file the QEMU process has access to. Access to the filesystem may be local or via a network share protocol such as CIFS.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2018-16872?

It affects 5 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Opensuse Leap, Qemu Qemu.

## How do I fix CVE-2018-16872?

Apply the vendor's patch.

## Is CVE-2018-16872 being exploited?

There is no known exploitation of CVE-2018-16872 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-16872 and fix it if it is affected.

What it is: CVE-2018-16872 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 13 Dec 2018. 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-2018-16872 in the wild and no public exploit code.

Affected product: Canonical Ubuntu 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-2018-16872/ (Markdown: https://insights.sbomify.com/CVE-2018-16872/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-16872
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-16872
- OSV: https://osv.dev/vulnerability/CVE-2018-16872

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-16872/
Summaries are generated and may contain mistakes; the official description above is the record.