CVE-2021-40085: Neutron OpenStack Neutron Vulnerable To Authenticated Vulnerability

HIGH
Advisory Identifier: GHSA-fh73-gjvg-349c
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CVSS 6.5
Published
Advisory Summary

CVE-2021-40085 is a HIGH (CVSS 6.5) openstack neutron vulnerable to authenticated vulnerability (General Security Weakness) affecting Neutron libraries in the PyPI ecosystem. The issue involves openstack neutron vulnerable to authenticated attackers reconfiguring dnsmasq via crafted extra_dhcp_opts value. Remediation is available by upgrading affected packages to version 16.4.1, 17.2.1, 18.1.1.

CVE-2021-40085 at a Glance

CVE Identifier CVE-2021-40085
GHSA Identifier GHSA-fh73-gjvg-349c
Severity HIGH
CVSS v3.1 Base Score 6.5
CWE Classification General Security Weakness
Affected Product Neutron
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2021-40085

To remediate this vulnerability, upgrade all affected Neutron dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

neutron fixed: 16.4.1 
pip install neutron>=16.4.1
neutron fixed: 17.2.1 
pip install neutron>=17.2.1
neutron fixed: 18.1.1 
pip install neutron>=18.1.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show neutron

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2021-40085, inspect your installed packages using pip:

pip show neutron

Analyze the terminal output to locate any version of Neutron in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 16.4.1), your application is affected.

Note: The pip show neutron command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under General Security Weakness. In Neutron, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2021-40085 Affected Neutron Versions

3 component(s)
Fixed Versions:
16.4.117.2.118.1.1
Product / Package Ecosystem Affected Versions Fixed Version
neutron
pypi/neutron
PyPI
< 16.4.1
16.4.1
neutron
pypi/neutron
PyPI
≥ 17.0.0
< 17.2.1
17.2.1
neutron
pypi/neutron
PyPI
≥ 18.0.0
< 18.1.1
18.1.1

References

NVD — CVE-2021-40085 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-40085
Security Fix Commit FIX COMMIT
https://github.com/openstack/neutron/commit/df891f0593d234e01f27d7c0376d9702e178ecfb
Neutron Source Repository REPOSITORY
https://github.com/openstack/neutron
Neutron Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/neutron/PYSEC-2021-361.yaml
launchpad.net/bugs/1939733 WEB
https://launchpad.net/bugs/1939733
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2021/10/msg00005.html
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2022/05/msg00038.html
Neutron Security Information SECURITY
https://security.openstack.org/ossa/OSSA-2021-005.html
Neutron Security Information SECURITY
https://www.debian.org/security/2021/dsa-4983
Neutron Security Information SECURITY
http://www.openwall.com/lists/oss-security/2021/08/31/2

Frequently Asked Questions

What is CVE-2021-40085?
CVE-2021-40085 is a security vulnerability in Neutron involving OpenStack Neutron vulnerable to authenticated attackers reconfiguring dnsmasq via crafted extra_dhcp_opts value under General Security Weakness.
Which Neutron versions are affected?
Affected versions include releases prior to 16.4.1, 17.2.1, 18.1.1 across affected packages: neutron.
What version fixes CVE-2021-40085?
Upgrading to 16.4.1, 17.2.1, 18.1.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is neutron affected?
Yes, neutron is affected in releases prior to 16.4.1, 17.2.1, 18.1.1. Upgrade your dependency to 16.4.1, 17.2.1, 18.1.1 or later.
What is the CVSS score of CVE-2021-40085?
CVE-2021-40085 has a CVSS v3.1 base score of 6.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2021-40085?
CVE-2021-40085 is classified under General Security Weakness.
How can I check PyPI dependencies for CVE-2021-40085?
Run the dependency tree command: 'pip show neutron'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fh73-gjvg-349c",
  "modified" : "2024-10-07T14:47:09Z",
  "published" : "2022-05-24T19:12:33Z",
  "aliases" : [ "CVE-2021-40085" ],
  "summary" : "OpenStack Neutron vulnerable to authenticated attackers reconfiguring dnsmasq via crafted extra_dhcp_opts value",
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "neutron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "16.4.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "neutron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "17.0.0"
      }, {
        "fixed" : "17.2.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "neutron"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "18.0.0"
      }, {
        "fixed" : "18.1.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-40085"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/openstack/neutron/commit/df891f0593d234e01f27d7c0376d9702e178ecfb"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/openstack/neutron"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/neutron/PYSEC-2021-361.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://launchpad.net/bugs/1939733"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2021/10/msg00005.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2022/05/msg00038.html"
  }, {
    "type" : "WEB",
    "url" : "https://security.openstack.org/ossa/OSSA-2021-005.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2021/dsa-4983"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2021/08/31/2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-02-23T21:38:57Z",
    "nvd_published_at" : "2021-08-31T18:15:00Z"
  }
}