{"cve":"CVE-2021-20267","nvd":{"published":"2021-05-28T19:15:07.483","modified":"2026-06-17T03:33:34.500","status":"Modified","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H","score":7.1},"cwes":["CWE-345"],"references":["https://bugzilla.redhat.com/show_bug.cgi?id=1934330","https://security.openstack.org/ossa/OSSA-2021-001.html","https://bugzilla.redhat.com/show_bug.cgi?id=1934330","https://security.openstack.org/ossa/OSSA-2021-001.html"],"products":["openstack:neutron","redhat:openstack_platform"],"source":"nvd","synced_at":"2026-10-19T21:18:09.669877188+00:00"},"epss":{"cve":"CVE-2021-20267","score":0.01023,"percentile":0.63518,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-w8hx-f868-pvch","url":"https://osv.dev/vulnerability/GHSA-w8hx-f868-pvch","summary":"Openstack Neutron has Insufficient Verification of IPv6 addresses","modified":"2024-09-26T15:10:49.249796Z","packages":[{"ecosystem":"PyPI","name":"neutron","purl":"pkg:pypi/neutron","ranges":[">=16.0.0 <16.3.1"],"fixed":["16.3.1"]},{"ecosystem":"PyPI","name":"neutron","purl":"pkg:pypi/neutron","ranges":["<15.3.3"],"fixed":["15.3.3"]},{"ecosystem":"PyPI","name":"neutron","purl":"pkg:pypi/neutron","ranges":[">=17.0.0 <17.1.1"],"fixed":["17.1.1"]}]},{"id":"PYSEC-2021-136","url":"https://osv.dev/vulnerability/PYSEC-2021-136","summary":"","modified":"2026-06-10T17:02:23.807508981Z","packages":[{"ecosystem":"PyPI","name":"neutron","purl":"pkg:pypi/neutron","ranges":["<15.3.3",">=16.0.0 <16.3.1",">=17.0.0 <17.1.1"],"fixed":["15.3.3","16.3.1","17.1.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}