CVE-2021-20267: High severity neutron vulnerability
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.
Other sources
VMs can send ICMPv6 Neighbor Advertisement packets with no check on their content to mis-direct traffic to them (source address spoofing). Pre-condition: two running VMs in the same L2 flat network with IPv6 connectivity
Upstream bug: https://bugs.launchpad.net/neutron/+bug/1902917 Upstream patch: https://review.opendev.org/c/openstack/neutron/+/776599
See also: https://bugzilla.redhat.com/showbug.cgi?id=1345892 (same issue but for OpenVSwitch driver instead of iptables)
— Red Hat
Affected Software
Remediation
Patch Available
Patch Available
Event History
Frequently Asked Questions
What is CVE-2021-20267?
CVE-2021-20267 is a vulnerability in openstack-neutron's default Open vSwitch firewall rules.
How can the vulnerability be exploited?
The vulnerability can be exploited by sending carefully crafted packets to impersonate the IPv6 addresses of other systems on the network.
What is the severity of CVE-2021-20267?
CVE-2021-20267 has a severity score of 7.1, which is considered high.
Which software versions are affected by CVE-2021-20267?
OpenStack Neutron versions up to and including 16.3.3, versions between 17.0.0 and 17.1.3, and version 18.0.0 are affected. Red Hat Openstack Platform versions 10.0, 13.0, 16.1, and 16.2 are also affected.
How can I fix CVE-2021-20267?
To fix CVE-2021-20267, update to OpenStack Neutron version 16.3.3, versions between 17.0.0 and 17.1.3, or version 18.0.0. For Red Hat Openstack Platform, update to versions 10.0, 13.0, 16.1, or 16.2.