# CVE-2023-42801: Stack buffer overflow due to `strcpy` into fixed size buffer in `extractVersionQuadFromString`

> A malicious game streaming server can crash Moonlight clients or potentially execute code via a stack buffer overflow in the shared client library.

- **Severity:** High 7.6 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 14 Dec 2023
- **Updated:** 2 Aug 2024
- **Also known as:** GHSA-f3h8-j898-5h5v

## What is CVE-2023-42801?

CVE-2023-42801 is a high-severity memory corruption vulnerability in moonlight-stream moonlight-common-c, published on 14 Dec 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Moonlight-common-c contains the core GameStream client code shared between Moonlight clients. Moonlight-common-c is vulnerable to buffer overflow starting in commit f57bd745b4cbed577ea654fad4701bea4d38b44c. A malicious game streaming server could exploit a buffer overflow vulnerability to crash a moonlight client. Achieving RCE is possible but unlikely, due to stack canaries in use by modern compiler toolchains. The published binaries for official clients Qt, Android, iOS/tvOS, and Embedded are built with stack canaries, but some unofficial clients may not use stack canaries. This vulnerability takes place after the pairing process, so it requires the client to be tricked into pairing to a malicious host. It is not possible to perform using a man-in-the-middle due to public key pinning that takes place during the pairing process. The bug was addressed in commit b2497a3918a6d79808d9fd0c04734786e70d5954.

Weakness: CWE-120 (Buffer Copy without Checking Size of Input)

## Which versions are affected by CVE-2023-42801?

It affects 8 products.


Products: Moonlight-Stream Moonlight, Moonlight-Stream Moonlight-Common-C, Moonlight-Stream Moonlight Embedded, Moonlight-Stream Moonlight Qt\/Pc, Moonlight-Stream Moonlight Switch, Moonlight-Stream Moonlight Tv, Moonlight-Stream Moonlight Vita, Moonlight-Stream Moonlight Xbox.

## How do I fix CVE-2023-42801?

No fix has been published for CVE-2023-42801 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-42801 being exploited?

There is no known exploitation of CVE-2023-42801 in the wild and no public exploit code.

## Other vulnerabilities in moonlight-stream moonlight-common-c

- [CVE-2023-42799](https://insights.sbomify.com/CVE-2023-42799/): Buffer overflow due to use of `strcpy` in `parseUrlAddrFromRtspUrlString` (high 8.8)
- [CVE-2023-42800](https://insights.sbomify.com/CVE-2023-42800/): Buffer overflow due to use of `strcpy` in `performRtspHandshake` (high 8.8)
- [CVE-2020-11024](https://insights.sbomify.com/CVE-2020-11024/): Man-in-the-middle attack in Moonlight iOS/tvOS (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-42801 and fix it if it is affected.

What it is: CVE-2023-42801 is a high-severity memory corruption vulnerability in moonlight-stream moonlight-common-c, published on 14 Dec 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2023-42801 in the wild and no public exploit code.

Affected product: moonlight-stream moonlight-common-c. 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-2023-42801/ (Markdown: https://insights.sbomify.com/CVE-2023-42801/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-42801
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-42801
- OSV: https://osv.dev/vulnerability/CVE-2023-42801

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-42801/
Summaries are generated and may contain mistakes; the official description above is the record.