What is CVE-2021-40085?

CVE-2021-40085 is a high-severity security vulnerability in neutron (pip), affecting versions < 16.4.1. It is fixed in 16.4.1, 17.2.1, 18.1.1.

How severe is CVE-2021-40085?

CVE-2021-40085 has a CVSS score of 6.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Which versions of neutron are affected by CVE-2021-40085?

neutron (pip) versions < 16.4.1 is affected.

Is there a fix for CVE-2021-40085?

Yes. CVE-2021-40085 is fixed in 16.4.1, 17.2.1, 18.1.1. Upgrade to this version or later.

Is CVE-2021-40085 exploitable, and should I be worried?

Whether CVE-2021-40085 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

What actually determines whether CVE-2021-40085 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

CVE-2021-40085 in neutron

Q: How severe is CVE-2021-40085?

CVE-2021-40085 has a CVSS score of 6.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.

Q: Which versions of neutron are affected by CVE-2021-40085?

neutron (pip) versions < 16.4.1 is affected.

Q: Is there a fix for CVE-2021-40085?

Yes. CVE-2021-40085 is fixed in 16.4.1, 17.2.1, 18.1.1. Upgrade to this version or later.

Q: Is CVE-2021-40085 exploitable, and should I be worried?

Whether CVE-2021-40085 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk.

Q: What actually determines whether CVE-2021-40085 is exploitable, and how bad it is?

Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.

Q: How do I fix CVE-2021-40085?

Upgrade: neutron to 16.4.1 or later, neutron to 17.2.1 or later, neutron to 18.1.1 or later.

Summary

OpenStack Neutron vulnerable to authenticated attackers reconfiguring dnsmasq via crafted extradhcpopts value

An issue was discovered in OpenStack Neutron before 16.4.1, 17.x before 17.2.1, and 18.x before 18.1.1. Authenticated attackers can reconfigure dnsmasq via a crafted extra_dhcp_opts value.

Impact

CVE-2021-40085 has a CVSS score of 6.5 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (16.4.1, 17.2.1, 18.1.1); upgrading removes the vulnerable code path.

Affected versions

neutron (< 16.4.1) neutron (>= 17.0.0, < 17.2.1) neutron (>= 18.0.0, < 18.1.1)

Security releases

neutron → 16.4.1 (pip) neutron → 17.2.1 (pip) neutron → 18.1.1 (pip)

Kodem intelligence

Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.

Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.

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Remediation advice

Upgrade the following packages to resolve this vulnerability:

neutron to 16.4.1 or later; neutron to 17.2.1 or later; neutron to 18.1.1 or later

Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.

Frequently Asked Questions

What is CVE-2021-40085? CVE-2021-40085 is a high-severity security vulnerability in neutron (pip), affecting versions < 16.4.1. It is fixed in 16.4.1, 17.2.1, 18.1.1.
How severe is CVE-2021-40085? CVE-2021-40085 has a CVSS score of 6.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
Which versions of neutron are affected by CVE-2021-40085? neutron (pip) versions < 16.4.1 is affected.
Is there a fix for CVE-2021-40085? Yes. CVE-2021-40085 is fixed in 16.4.1, 17.2.1, 18.1.1. Upgrade to this version or later.
Is CVE-2021-40085 exploitable, and should I be worried? Whether CVE-2021-40085 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
What actually determines whether CVE-2021-40085 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
How do I fix CVE-2021-40085?
- Upgrade neutron to 16.4.1 or later
- Upgrade neutron to 17.2.1 or later
- Upgrade neutron to 18.1.1 or later

Other vulnerabilities in neutron

CVE-IDSeverityPackage summary

CVE-2026-49299Mediumneutron: OpenStack Neutron has an Incorrect Authorization issue CVE-2024-53916Mediumneutron: OpenStack Neutron can use an incorrect ID during policy enforcement CVE-2023-3637Mediumneutron: Denial of service in neutron CVE-2022-3277Mediumneutron: openstack-neutron uncontrolled resource consumption flaw CVE-2021-40797Highneutron: OpenStack Neutron Denial of Service vulnerability