Vulnerability record · CVE-2021-20267 · published 28 May 2021

CVE-2021-20267: Openstack neutron insufficient verification of data authenticity vulnerability

Openstack · Neutron

A flaw was found in openstack-neutron's default Open vSwitch firewall rules. By sending carefully crafted packets, anyone in control of a server instance connected to the virtual switch can impersonate the IPv6 addresses of other systems on the network, resulting in denial of service or in some cases possibly interception of traffic intended for other destinations. Only deployments using the Open vSwitch driver are affected. Source: OpenStack project. Versions before openstack-neutron 15.3.3, openstack-neutron 16.3.1 and openstack-neutron 17.1.1 are affected.

7.1 CVSS 3.1 High EPSS 1.0% · top 37.9% CWE-345 · Insufficient verification of data authenticity

7.1CVSS 3.1 base score, v2 5.5

1.0%EPSS exploitation probability, 30 days

NoNot in CISA KEV

2Affected product versions listed by NVD

4References

17 Jun 2026Last modified by NVD

Description

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

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Neutron Openstack

Openstack Platform Redhat

References

Link	Tags
https://bugzilla.redhat.com/show_bug.cgi?id=1934330	Issue TrackingPatchThird Party Advisory
https://security.openstack.org/ossa/OSSA-2021-001.html	PatchVendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1934330	Issue TrackingPatchThird Party Advisory
https://security.openstack.org/ossa/OSSA-2021-001.html	PatchVendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-20267), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.