# CVE-2026-106429: Application denial of service via malformed KMS endpoint in MongoDB libmongocrypt

> An integer underflow in libmongocrypt allows an authenticated user to cause a denial of service by triggering an allocation failure via malformed KMS endpoints.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Oct 2026
- **Updated:** 8 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-106429, UBUNTU-CVE-2026-106429

## What is CVE-2026-106429?

CVE-2026-106429 is a high-severity vulnerability in MongoDB libmongocrypt, published on 8 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

An integer underflow in the KMS endpoint-parsing logic of MongoDB libmongocrypt can cause an allocation failure that terminates the application process. This can occur when an authenticated user modifies a key document in the key vault collection, or when an application accepts a KMS endpoint containing a colon after its path or query during key creation. The issue does not access memory outside its allocated bounds.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound))

## Which versions are affected by CVE-2026-106429?


## How do I fix CVE-2026-106429?

Upgrade to a fixed version.

## Is CVE-2026-106429 being exploited?

There is no known exploitation of CVE-2026-106429 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-106429 and fix it if it is affected.

What it is: CVE-2026-106429 is a high-severity vulnerability in MongoDB libmongocrypt, published on 8 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-106429 in the wild and no public exploit code.

Affected product: MongoDB libmongocrypt. 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-2026-106429/ (Markdown: https://insights.sbomify.com/CVE-2026-106429/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-106429
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-106429
- OSV: https://osv.dev/vulnerability/CVE-2026-106429

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-106429/
Summaries are generated and may contain mistakes; the official description above is the record.