# CVE-2019-14842: Integer overflow in libnbd

> A signed/unsigned confusion in libnbd allows a malicious NBD server to overwrite memory and execute arbitrary code on the client.

- **Severity:** High 7.3 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Nov 2019
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-14842, GHSA-xv5g-h355-j9v9

## What is CVE-2019-14842?

CVE-2019-14842 is a high-severity vulnerability in [UNKNOWN] libnbd, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Structured reply is a feature of the newstyle NBD protocol allowing the server to send a reply in chunks. A bounds check which was supposed to test for chunk offsets smaller than the beginning of the request did not work because of signed/unsigned confusion. If one of these chunks contains a negative offset then data under control of the server is written to memory before the read buffer supplied by the client. If the read buffer is located on the stack then this allows the stack return address from nbd_pread() to be trivially modified, allowing arbitrary code execution under the control of the server. If the buffer is located on the heap then other memory objects before the buffer can be overwritten, which again would usually lead to arbitrary code execution.

Weakness: CWE-681 (Incorrect Conversion between Numeric Types)

## Which versions are affected by CVE-2019-14842?

It affects 1 product.


Products: Redhat Libnbd.

## How do I fix CVE-2019-14842?

Apply the vendor's patch.

## Is CVE-2019-14842 being exploited?

There is no known exploitation of CVE-2019-14842 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-14842 and fix it if it is affected.

What it is: CVE-2019-14842 is a high-severity vulnerability in [UNKNOWN] libnbd, published on 26 Nov 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-14842 in the wild and no public exploit code.

Affected product: [UNKNOWN] libnbd. 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-2019-14842/ (Markdown: https://insights.sbomify.com/CVE-2019-14842/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-14842
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-14842
- OSV: https://osv.dev/vulnerability/CVE-2019-14842

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-14842/
Summaries are generated and may contain mistakes; the official description above is the record.