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OpenStack oslo.messaging CVE-2026-44393

| EUVDEUVD-2026-34294 HIGH
Improper Validation of Certificate with Host Mismatch (CWE-297)
2026-06-04 mitre GHSA-76qh-xr7q-h39m
7.4
CVSS 3.1 · Vendor: mitre
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Severity by source

Vendor (mitre) PRIMARY
7.4 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
SUSE
HIGH
qualitative
Red Hat
7.4 HIGH
qualitative

Primary rating from Vendor (mitre).

CVSS VectorVendor: mitre

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Lifecycle Timeline

3
Analysis Generated
Jun 04, 2026 - 18:22 vuln.today
CVSS changed
Jun 04, 2026 - 18:22 NVD
7.4 (HIGH)
CVE Published
Jun 04, 2026 - 00:00 nvd
UNKNOWN (no severity yet)

DescriptionCVE.org

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.

AnalysisAI

Man-in-the-middle attack against OpenStack oslo.messaging 1.0.0 through 17.3.0 is possible because the RabbitMQ driver validates the certificate chain but skips TLS hostname verification, letting any cert signed by the deployment CA impersonate the broker. An attacker positioned on the control-plane network can intercept and tamper with RPC and notification traffic between OpenStack services, with no public exploit identified at time of analysis but a credible POC pathway documented in OSSN-0096.

Technical ContextAI

oslo.messaging is the RPC and notification abstraction library underpinning nearly every OpenStack service (Nova, Neutron, Cinder, Keystone notifications, etc.) when RabbitMQ is the messaging backend. The bug is a classic CWE-297 (Improper Validation of Certificate with Host Mismatch): when ssl_ca_file is set, the Python SSL context performs chain validation but the broker hostname is never passed to the TLS handshake (server_hostname / check_hostname is not enforced), so SNI-bound name checks are bypassed. Any certificate issued by the same internal CA - including one issued for an unrelated host or a compromised low-trust service - is accepted as a valid broker identity, collapsing the trust model to 'signed by our CA' rather than 'is the broker we expect.'

RemediationAI

No vendor-released patch identified at time of analysis from the provided references - both links point to the Launchpad bug report and OSSN-0096 rather than a tagged oslo.messaging release, so operators should monitor those pages for the fixed version and upgrade once published (the fix will set server_hostname on the SSL wrap and enable hostname verification). As a compensating control, restrict the control-plane network so only OpenStack hosts and the RabbitMQ cluster can reach the AMQP TLS port (typically 5671), which removes the on-path prerequisite at the cost of stricter network segmentation; alternatively, issue RabbitMQ broker certificates from a dedicated CA used for nothing else and rotate any existing broker certs, which limits abusable certs to a much smaller pool but requires PKI changes. Mutual TLS (client cert auth) on the RabbitMQ listener further raises the bar but requires distributing client certificates to every oslo.messaging consumer.

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Vendor StatusVendor

SUSE

Severity: High
Product Status
openSUSE Tumbleweed Fixed

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CVE-2026-44393 vulnerability details – vuln.today

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