# CVE-2021-20267: Openstack Neutron has Insufficient Verification of IPv6 addresses

Source: https://junglewise.ai/threats/cve-2021-20267-openstack-neutron-has-insufficient-verification-of-ipv6-addresses  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-05-28  
License: CC BY 4.0 with a link back

CVE-2021-20267 · Severity: low · CVSS 3.1 · Published 2021-05-28

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.

Technologies: [neutron (PyPI)](https://junglewise.ai/threats/technologies/pypi-neutron). Vendors: [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2021-20267 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2021-20267 being exploited in the wild.

**How severe is CVE-2021-20267?** Low severity, with a CVSS score of 3.1, published 28 May 2021.

**Which products and versions are affected?** neutron (PyPI) ECOSYSTEM:introduced=0,fixed=15.3.3,introduced=16.0.0,fixed=16.3.1,introduced=17.0.0,fixed=17.1.1, ECOSYSTEM:introduced=16.0.0,fixed=16.3.1.

**Is there a fix for CVE-2021-20267?** Yes. neutron (PyPI): upgrade to 16.3.1, 17.1.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**Am I affected by CVE-2021-20267?** Check whether you run neutron (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- neutron (PyPI): upgrade to 16.3.1, 17.1.1 or later

  ```sh
  pip install "neutron>=17.1.1"
  ```


## Affected products

- neutron (PyPI) ECOSYSTEM:introduced=0,fixed=15.3.3,introduced=16.0.0,fixed=16.3.1,introduced=17.0.0,fixed=17.1.1, ECOSYSTEM:introduced=16.0.0,fixed=16.3.1

## Identifiers

- CVE-2021-20267
- GHSA-w8hx-f868-pvch
- PYSEC-2021-136

## Related threats

- [PYSEC-2026-1693 - OpenStack Neutron can use an incorrect ID during policy enforcement](https://junglewise.ai/threats/cve-2024-53916-openstack-neutron-can-use-an-incorrect-id-during-policy)
- [PYSEC-2026-1694 - Denial of service in neutron](https://junglewise.ai/threats/cve-2023-3637-denial-of-service-in-neutron)
- [PYSEC-2026-855 - openstack-neutron uncontrolled resource consumption flaw](https://junglewise.ai/threats/cve-2022-3277-openstack-neutron-uncontrolled-resource-consumption-flaw)
- [PYSEC-2026-851 - OpenStack Neutron Improper Authentication vulnerability](https://junglewise.ai/threats/cve-2014-0056-openstack-neutron-improper-authentication-vulnerability)
- [PYSEC-2026-853 - OpenStack Neutron Race condition vulnerability](https://junglewise.ai/threats/cve-2015-5240-openstack-neutron-race-condition-vulnerability)