# CVE-2026-44393: OpenStack oslo.messaging does not verify RabbitMQ broker hostname during TLS handshake

> Attackers can intercept OpenStack RPC traffic via man-in-the-middle attacks due to missing TLS hostname verification in the RabbitMQ driver.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Jun 2026
- **Updated:** 27 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-44393, GHSA-76qh-xr7q-h39m, PYSEC-2026-3492, UBUNTU-CVE-2026-44393, openSUSE-SU-2026:10973-1

## What is CVE-2026-44393?

CVE-2026-44393 is a high-severity vulnerability in n/a, published on 4 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in OpenStack oslo.messaging 1.0.0 through 17.3.0. The oslo.messaging RabbitMQ driver does not perform TLS hostname verification when connecting to the message broker. When ssl_ca_file is configured, the driver enables certificate chain validation but does not pass the expected broker hostname into the underlying TLS stack. Any certificate signed by the deployment CA is accepted regardless of hostname, allowing an attacker who can intercept control-plane traffic to impersonate the RabbitMQ broker and perform a man-in-the-middle attack on RPC and notification traffic. All OpenStack services using oslo.messaging with RabbitMQ over TLS are affected.

Weakness: CWE-295 (Improper Certificate Validation), CWE-297 (Improper Validation of Certificate with Host Mismatch)

## Which versions are affected by CVE-2026-44393?

3 open source packages ship an affected version, including oslo-messaging and oslo.messaging.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `oslo-messaging` | PyPI | From 1.0.0 to 17.3.0 | None |
| `oslo-messaging` | PyPI | From 1.0.0 to 17.3.0 | None |
| `oslo.messaging` | PyPI | From 1.0.0 to 17.3.0 | None |
| `python-oslo.messaging` | openSUSE:Tumbleweed | All versions | 18.1.0-1.1 |

## How do I fix CVE-2026-44393?

Upgrade to a fixed version.

## Is CVE-2026-44393 being exploited?

There is no known exploitation of CVE-2026-44393 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-44393 and fix it if it is affected.

What it is: CVE-2026-44393 is a high-severity vulnerability in n/a, published on 4 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-44393 in the wild and no public exploit code.

Affected packages and fixed versions:
- oslo-messaging (PyPI): affected from 1.0.0 up to 17.3.0; no fix listed
- oslo-messaging (PyPI): affected from 1.0.0 up to 17.3.0; no fix listed
- oslo.messaging (PyPI): affected from 1.0.0 up to 17.3.0; no fix listed

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-2026-44393/ (Markdown: https://insights.sbomify.com/CVE-2026-44393/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-44393
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-44393
- OSV: https://osv.dev/vulnerability/CVE-2026-44393

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-44393/
Summaries are generated and may contain mistakes; the official description above is the record.