# CVE-2026-96746: Heap buffer overflow via mid-scan command list growth in client topology monitoring

> An attacker controlling DNS and host responses can trigger a heap buffer overflow in the MongoDB C Driver, causing application crashes.

- **Severity:** High 8.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Sep 2026
- **Updated:** 24 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-96746, GHSA-frjf-h5jg-4v46, UBUNTU-CVE-2026-96746

## What is CVE-2026-96746?

CVE-2026-96746 is a high-severity memory corruption vulnerability in MongoDB C Driver, published on 24 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An out-of-bounds write in the connection-monitoring logic of the MongoDB C Driver may allow an unauthenticated party who controls name resolution and the responses of the hosts named in a client's connection string to write beyond the end of a heap buffer. This may cause the application using the driver to terminate unexpectedly.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-96746?


## How do I fix CVE-2026-96746?

Apply the vendor's patch.

## Is CVE-2026-96746 being exploited?

There is no known exploitation of CVE-2026-96746 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-96746 and fix it if it is affected.

What it is: CVE-2026-96746 is a high-severity memory corruption vulnerability in MongoDB C Driver, published on 24 Sep 2026. 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-2026-96746 in the wild and no public exploit code.

Affected product: MongoDB C Driver. 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-2026-96746/ (Markdown: https://insights.sbomify.com/CVE-2026-96746/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-96746
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-96746
- OSV: https://osv.dev/vulnerability/CVE-2026-96746

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-96746/
Summaries are generated and may contain mistakes; the official description above is the record.