# CVE-2018-12633: Race condition in n/a

> A race condition in the VirtualBox guest driver allows local attackers to cause kernel errors, leading to denial of service and information leakage.

- **Severity:** Medium 6.3 (`CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/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:** 22 Jun 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-12633, GHSA-9rwp-mqvh-8g6q, UBUNTU-CVE-2018-12633

## What is CVE-2018-12633?

CVE-2018-12633 is a medium-severity vulnerability in Linux kernel, published on 22 Jun 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An issue was discovered in the Linux kernel through 4.17.2. vbg_misc_device_ioctl() in drivers/virt/vboxguest/vboxguest_linux.c reads the same user data twice with copy_from_user. The header part of the user data is double-fetched, and a malicious user thread can tamper with the critical variables (hdr.size_in and hdr.size_out) in the header between the two fetches because of a race condition, leading to severe kernel errors, such as buffer over-accesses. This bug can cause a local denial of service and information leakage.

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

## Which versions are affected by CVE-2018-12633?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2018-12633?

Apply the vendor's patch.

## Is CVE-2018-12633 being exploited?

There is no known exploitation of CVE-2018-12633 in the wild and no public exploit code.

Public exploit code:

- A technical case study and exploitation analysis of the Authentication Bypass vulnerability in TP-Link TL-WR840N firmware (CVE-2018-12633). (github_poc): https://github.com/wiliam227user/CVE-2018-12633-TPLink-Auth-Bypass

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-12633 and fix it if it is affected.

What it is: CVE-2018-12633 is a medium-severity vulnerability in Linux kernel, published on 22 Jun 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-2018-12633 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2018-12633/ (Markdown: https://insights.sbomify.com/CVE-2018-12633/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-12633
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-12633
- OSV: https://osv.dev/vulnerability/CVE-2018-12633

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-12633/
Summaries are generated and may contain mistakes; the official description above is the record.