# CVE-2026-93856: OpenStack Cinder cross-project information disclosure in Messages API

Source: https://junglewise.ai/threats/cve-2026-93856-in-openstack-cinder-through-29-0-0-cross-project-information  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-21. Updated: 2026-10-21  
License: CC BY 4.0 with a link back

CVE-2026-93856 · Severity: medium · CVSS 4.3 · Published 2026-10-21

OpenStack Cinder is a block storage service that manages virtual storage volumes in cloud environments. A flaw in Cinder's Messages API allows a user with limited read access to one project to view messages and resource identifiers from all other projects in the deployment. An attacker can exploit this to discover infrastructure details, resource UUIDs, and operational metadata across projects they should not have access to.

Vendors: [OpenStack](https://junglewise.ai/threats/vendors/openstack).

## Quick answers

**Is CVE-2026-93856 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-93856 being exploited in the wild.

**How severe is CVE-2026-93856?** Medium severity, with a CVSS score of 4.3, published 21 October 2026.

**Which products and versions are affected?** OpenStack Cinder >=9.0.0, <26.3.1; ==27.0.0; ==28.0.0; ==29.0.0.

**Is there a fix for CVE-2026-93856?** Yes: fixed in Cinder 26.3.1, 2025.1 (Epoxy), 2025.2 (Flamingo), 2026.1 (Gazpacho), 2026.2 (Hibiscus), 2027.1 (Indri). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-93856 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-93856?** Check whether you run OpenStack Cinder at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Cinder 26.3.1, 2025.1 (Epoxy), 2025.2 (Flamingo), 2026.1 (Gazpacho), 2026.2 (Hibiscus), 2027.1 (Indri)

## Technical details

The MessagesController.index endpoint fails to scope the database query to the caller's project, allowing any project-scoped 'member' or 'reader' role to retrieve messages from all projects. The vulnerability stems from missing project filtering in the message_get_all database path; while the authorization policy is project-scoped, the actual query lacks a project_id filter. An attacker with legitimate project-scoped credentials can call GET /v3/messages and receive responses containing resource UUIDs and messages from other projects.

## Affected products

- OpenStack Cinder >=9.0.0, <26.3.1; ==27.0.0; ==28.0.0; ==29.0.0

## Timeline

- 2026-07-15: disclosed
- 2026-10-20: advisory
- 2026-10-20: patched

## References

- [https://bugs.launchpad.net/cinder/+bug/2160671](https://bugs.launchpad.net/cinder/+bug/2160671)
- [https://security.openstack.org/ossa/OSSA-2026-045.html](https://security.openstack.org/ossa/OSSA-2026-045.html)