# CVE-2023-39946: Heap overflow in push_back_helper due to a CDR message

> A heap overflow in eProsima Fast DDS allows remote attackers to crash processes via malicious CDR messages on the discovery multicast port.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Aug 2023
- **Updated:** 13 Feb 2025
- **Also known as:** DEBIAN-CVE-2023-39946, GHSA-j297-rg6j-m7hx, UBUNTU-CVE-2023-39946

## What is CVE-2023-39946?

CVE-2023-39946 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 11 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

eprosima Fast DDS is a C++ implementation of the Data Distribution Service standard of the Object Management Group. Prior to versions 2.11.1, 2.10.2, 2.9.2, and 2.6.6, heap can be overflowed by providing a PID_PROPERTY_LIST parameter that contains a CDR string with length larger than the size of actual content. In `eprosima::fastdds::dds::ParameterPropertyList_t::push_back_helper`, `memcpy` is called to first copy the octet'ized length and then to copy the data into `properties_.data`. At the second memcpy, both `data` and `size` can be controlled by anyone that sends the CDR string to the discovery multicast port. This can remotely crash any Fast-DDS process. Versions 2.11.1, 2.10.2, 2.9.2, and 2.6.6 contain a patch for this issue.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2023-39946?

It affects 2 products.


Products: Debian Debian Linux, Eprosima Fast Dds.

## How do I fix CVE-2023-39946?

Upgrade to a fixed version.

## Is CVE-2023-39946 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-39946 exists.

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- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-39946 and fix it if it is affected.

What it is: CVE-2023-39946 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 11 Aug 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-39946 exists.

Affected product: Debian Debian 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-2023-39946/ (Markdown: https://insights.sbomify.com/CVE-2023-39946/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-39946
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-39946
- OSV: https://osv.dev/vulnerability/CVE-2023-39946

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-39946/
Summaries are generated and may contain mistakes; the official description above is the record.