# CVE-2026-95843: Moquette malformed shared subscriptions can crash command processing

> A remote attacker can crash the MQTT broker's command processing loop by sending a malformed shared subscription filter, denying service to other clients.

- **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:** 23 Sep 2026

## What is CVE-2026-95843?

CVE-2026-95843 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, PostOffice.subscribe parses a shared-subscription filter through SharedSubscriptionUtils.extractShareName before validating the complete $share/{shareName}/{topicFilter} structure. A remote client can send a filter such as $share/grp without a topic-filter portion, causing a StringIndexOutOfBoundsException while calculating the share name. The exception terminates command handling on the shared session event loop and can deny service to other client sessions assigned to that loop. This issue is fixed in version 0.18.1.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-95843?

It affects 1 product.


Products: Moquette Moquette.

## How do I fix CVE-2026-95843?

No fix has been published for CVE-2026-95843 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-95843 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-95843 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-2026-95844](https://insights.sbomify.com/CVE-2026-95844/): Moquette deeply nested MQTT topics can cause stack exhaustion (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-95843 and fix it if it is affected.

What it is: CVE-2026-95843 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-2026-95843 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-2026-95843/ (Markdown: https://insights.sbomify.com/CVE-2026-95843/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-95843
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-95843
- OSV: https://osv.dev/vulnerability/CVE-2026-95843

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-95843/
Summaries are generated and may contain mistakes; the official description above is the record.