# CVE-2026-6811: PHP Stack Exhaustion

> Attackers can crash applications using the MongoDB PHP driver by sending deeply nested BSON documents from non-MongoDB sources.

- **Severity:** Medium 6.0 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:N/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:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 14 May 2026
- **Updated:** 15 May 2026
- **Also known as:** DEBIAN-CVE-2026-6811, GHSA-vc69-vr6f-4x67, UBUNTU-CVE-2026-6811

## What is CVE-2026-6811?

CVE-2026-6811 is a medium-severity denial of service vulnerability in MongoDB Inc. PHP Driver, published on 14 May 2026. 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

Stack exhaustion vulnerability in the MongoDB PHP driver can cause application crashes when processing deeply nested BSON documents in unusual circumstances when the source of these BSON documents is not MongoDB Server.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2026-6811?

It affects 1 product.


Products: Mongodb Php Driver.

## How do I fix CVE-2026-6811?

Upgrade to a fixed version.

## Is CVE-2026-6811 being exploited?

There is no known exploitation of CVE-2026-6811 in the wild and no public exploit code.

## Other vulnerabilities in MongoDB Inc. PHP Driver

- [CVE-2026-81525](https://insights.sbomify.com/CVE-2026-81525/): Cross-tenant database retargeting via dot/NUL injection in namespace strings in the PHP Driver (high 8.6)
- [CVE-2026-84968](https://insights.sbomify.com/CVE-2026-84968/): Heap out-of-bounds read via corrupt nested BSON in field path error message (medium 6.9)
- [CVE-2026-106436](https://insights.sbomify.com/CVE-2026-106436/): Application denial of service and data truncation via unchecked BSON append failures in MongoDB PHP Driver (medium 6.3)
- [CVE-2026-106432](https://insights.sbomify.com/CVE-2026-106432/): Heap buffer overflow via 32-bit string-length truncation in MongoDB PHP Driver (low 2.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-6811 and fix it if it is affected.

What it is: CVE-2026-6811 is a medium-severity denial of service vulnerability in MongoDB Inc. PHP Driver, published on 14 May 2026. 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-2026-6811 in the wild and no public exploit code.

Affected product: MongoDB Inc. PHP 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-2026-6811/ (Markdown: https://insights.sbomify.com/CVE-2026-6811/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-6811
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-6811
- OSV: https://osv.dev/vulnerability/CVE-2026-6811

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-6811/
Summaries are generated and may contain mistakes; the official description above is the record.