# CVE-2026-95844: Moquette deeply nested MQTT topics can cause stack exhaustion

> Remote attackers can cause denial of service in Moquette MQTT broker by publishing deeply nested topics that trigger stack exhaustion.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/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:** Not needed
- **Fix available:** No
- **Published:** 23 Sep 2026
- **Updated:** 29 Sep 2026

## What is CVE-2026-95844?

CVE-2026-95844 is a high-severity denial of service vulnerability in moquette-io moquette, published on 23 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, Moquette does not limit the depth of topic names and topic filters before processing them through recursive CTrie insertion and matching operations. A remote client can publish or subscribe with a deeply nested topic, causing a StackOverflowError that disrupts session processing and can deny service to broker clients. This issue is fixed in version 0.18.1.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2026-95844?

It affects 1 product.


Products: Moquette Moquette.

## How do I fix CVE-2026-95844?

No fix has been published for CVE-2026-95844 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-95844 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-95844 exists.

## Other vulnerabilities in moquette-io moquette

- [CVE-2026-85724](https://insights.sbomify.com/CVE-2026-85724/): Moquette pattern ACL wildcard injection allows cross-tenant authorization bypass (critical 9.6)
- [CVE-2026-95848](https://insights.sbomify.com/CVE-2026-95848/): Moquette fails open when configured authentication or authorization classes cannot load (critical 9.3)
- [CVE-2026-95847](https://insights.sbomify.com/CVE-2026-95847/): Moquette client IDs can cause cross-session H2 durable-queue corruption (high 8.8)
- [CVE-2026-95842](https://insights.sbomify.com/CVE-2026-95842/): Moquette uncaught MQTT command exceptions can terminate shared session event loops (high 8.7)
- [CVE-2026-95843](https://insights.sbomify.com/CVE-2026-95843/): Moquette malformed shared subscriptions can crash command processing (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-95844 and fix it if it is affected.

What it is: CVE-2026-95844 is a high-severity denial of service vulnerability in moquette-io moquette, published on 23 Sep 2026. 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-2026-95844 exists.

Affected product: moquette-io moquette. 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-2026-95844/ (Markdown: https://insights.sbomify.com/CVE-2026-95844/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-95844
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-95844
- OSV: https://osv.dev/vulnerability/CVE-2026-95844

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-95844/
Summaries are generated and may contain mistakes; the official description above is the record.