# CVE-2019-4656: Denial of service in MQ

> An authenticated user can crash the IBM MQ queue by triggering an error processing error messages, requiring a restart.

- **Severity:** Medium 6.5 (`CVSS:3.0/UI:N/C:N/S:U/A:H/I:N/AC:L/PR:L/AV:N/RC:C/E:U/RL:O`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Mar 2020
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-8vcg-h82j-6975

## What is CVE-2019-4656?

CVE-2019-4656 is a medium-severity denial of service vulnerability in Ibm Mq, published on 16 Mar 2020. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

IBM MQ and IBM MQ Appliance 7.1, 7.5, 8.0, 9.0 LTS, 9.1 LTS, and 9.1 CD is vulnerable to a denial of service attack that would allow an authenticated user to crash the queue and require a restart due to an error processing error messages. IBM X-Force ID: 170967.

## Which versions are affected by CVE-2019-4656?

It affects 3 products.


Products: Ibm Mq, Ibm Mq Appliance, Ibm Websphere Mq.

## How do I fix CVE-2019-4656?

No fix has been published for CVE-2019-4656 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-4656 being exploited?

There is no known exploitation of CVE-2019-4656 in the wild and no public exploit code.

## Other vulnerabilities in Ibm Mq

- [CVE-2026-10575](https://insights.sbomify.com/CVE-2026-10575/): IBM MQ queue manager is vulnerable to remote code execution (high 8.8)
- [CVE-2026-11375](https://insights.sbomify.com/CVE-2026-11375/): IBM MQ queue manager is vulnerable to remote code execution (high 8.8)
- [CVE-2026-11378](https://insights.sbomify.com/CVE-2026-11378/): IBM MQ queue manager is vulnerable to remote code execution (high 8.8)
- [CVE-2022-22489](https://insights.sbomify.com/CVE-2022-22489/): XML external entity in MQ (high 8.2)
- [CVE-2026-10027](https://insights.sbomify.com/CVE-2026-10027/): IBM MQ queue manager is vulnerable to unauthenticated remote code execution (high 8.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-4656 and fix it if it is affected.

What it is: CVE-2019-4656 is a medium-severity denial of service vulnerability in Ibm Mq, published on 16 Mar 2020. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-4656 in the wild and no public exploit code.

Affected product: Ibm Mq. 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-2019-4656/ (Markdown: https://insights.sbomify.com/CVE-2019-4656/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-4656
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-4656
- OSV: https://osv.dev/vulnerability/CVE-2019-4656

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-4656/
Summaries are generated and may contain mistakes; the official description above is the record.