CVE-2026-55707

openstack-neutron: openstack-neutron: Shared-network consumer can re-scope another project's subnets via subnetpool onboarding

Published Aug 5, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed
Description
In OpenStack Neutron before 28.0.2, the subnetpool onboarding API does not verify ownership of the target subnets. An authenticated user can onboard subnets from another project's shared network into their own subnetpool, mutating the victim's subnet state and altering L3 routing and address scope behavior for victim routers.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4735-1 neutron security update
Debian DSA Debian DSA DSA-6444-1 neutron security update
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description An authorization bypass was found in the OpenStack Neutron subnetpool onboarding API endpoint (PUT /v2.0/subnetpools/{id}/onboard_network_subnets). When a caller supplies a network_id, the API only verifies that the network is visible to the caller but does not verify that the caller owns the subnets on that network. When a network is RBAC-shared or globally shared, any project member with network visibility can invoke the API to onboard another project's subnets into the caller's own subnetpool, mutating the victim's subnet records (setting subnetpool_id to the attacker-controlled pool). If the attacker's subnetpool is associated with an address scope, Neutron syncs the victim's router interfaces with the attacker-controlled address scope, silently altering L3 routing, NAT, and address-scope behavior. The upstream fix adds an ownership check ensuring the caller has admin-or-owner authority over each subnet being onboarded, not merely visibility of the parent network. In OpenStack Neutron before 28.0.2, the subnetpool onboarding API does not verify ownership of the target subnets. An authenticated user can onboard subnets from another project's shared network into their own subnetpool, mutating the victim's subnet state and altering L3 routing and address scope behavior for victim routers.
CPEs cpe:2.3:a:openstack:neutron:*:*:*:*:*:*:*:*
References
Metrics cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N'}

Type Values Removed Values Added
First Time appeared Openstack
Openstack neutron
Vendors & Products Openstack
Openstack neutron
Type Values Removed Values Added
Description An authorization bypass was found in the OpenStack Neutron subnetpool onboarding API endpoint (PUT /v2.0/subnetpools/{id}/onboard_network_subnets). When a caller supplies a network_id, the API only verifies that the network is visible to the caller but does not verify that the caller owns the subnets on that network. When a network is RBAC-shared or globally shared, any project member with network visibility can invoke the API to onboard another project's subnets into the caller's own subnetpool, mutating the victim's subnet records (setting subnetpool_id to the attacker-controlled pool). If the attacker's subnetpool is associated with an address scope, Neutron syncs the victim's router interfaces with the attacker-controlled address scope, silently altering L3 routing, NAT, and address-scope behavior. The upstream fix adds an ownership check ensuring the caller has admin-or-owner authority over each subnet being onboarded, not merely visibility of the parent network.
Title openstack-neutron: openstack-neutron: Shared-network consumer can re-scope another project's subnets via subnetpool onboarding
Weaknesses CWE-863
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L'}

threat_severity

Important

Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Aug 12, 2026, 7:23 PM
Reserved
Jun 17, 2026, 1:24 AM
Status
Deferred
Published
Aug 5, 2026, 6:16 AM
Modified
Oct 24, 2026, 4:10 PM
Severity
Important
Public date
Jul 29, 2026, 3:00 PM