OpenStack Neutron: Neutron port RBAC policy bypass allows project managers to set trusted device owners on shared networks

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

2.2 · CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:N

EPSS

• CVE-2026-50266: 0.26% estimated exploitation activity in the next 30 days; percentile 18.12 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

In OpenStack Neutron before 28.0.1, a project manager can create or update a port on a shared network owned by another project and set deviceowner to a value that has "network:" at the beginning ("network:dhcp" for example). The default port RBAC policies incorrectly included PROJECTMANAGER without requiring network ownership, allowing any project manager to obtain trusted network-service port behavior on shared networks. Depending on backend and deployment, this can bypass anti-spoofing and security group protections, enabling DHCP, MAC, or IP spoofing against other tenants on the shared network. This is a regression of CVE-2015-5240 (OSSA-2015-018).

Published by the source

4 Jun 2026, 18:30 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-qmc5-gv6v-8p22

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-qmc5-gv6v-8p22

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# Patch Next advisory brief: CVE-2026-50266

Advisory: OpenStack Neutron: Neutron port RBAC policy bypass allows project managers to set trusted device owners on shared networks
IDs: CVE-2026-50266, GHSA-qmc5-gv6v-8p22
Record: https://patchnext.com/advisories/cve-2026-50266 (revision 2, source checked 26 Oct 2026, 13:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: neutron 28.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI neutron: affected < 28.0.1; fixed in 28.0.1

## Suggested inspection (read-only)
- `python -m pip show neutron`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on neutron.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-qmc5-gv6v-8p22 (OSV record GHSA-qmc5-gv6v-8p22 lists affected ranges: PyPI neutron >=0 <28.0.1 (fixed))
- Verified: https://github.com/advisories/GHSA-qmc5-gv6v-8p22 (GitHub-reviewed advisory GHSA-qmc5-gv6v-8p22 lists affected ranges: PyPI neutron >=0 <28.0.1)

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