CVE-2021-40797: Neutron Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-cpx3-696p-3cw9
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CVSS 6.5
CWE-772
Published
Advisory Summary

CVE-2021-40797 is a HIGH (CVSS 6.5) denial of service vulnerability (CWE-772: Missing Release of Resource after Effective Lifetime) affecting Neutron libraries in the PyPI ecosystem. The issue involves openstack neutron denial of service vulnerability. Remediation is available by upgrading affected packages to version 16.4.1, 17.2.1, 18.1.1.

CVE-2021-40797 at a Glance

CVE Identifier CVE-2021-40797
GHSA Identifier GHSA-cpx3-696p-3cw9
Severity HIGH
CVSS v3.1 Base Score 6.5
CWE Classification CWE-772: Missing Release of Resource after Effective Lifetime
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:N/A:H).

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 None (I:N)
Availability High (A:H)

How to Fix CVE-2021-40797

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-2021-40797, 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 CWE-772: Missing Release of Resource after Effective Lifetime, where the product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed. 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 the routes middleware in OpenStack Neutron before 16.4.1, 17.x before 17.2.1, and 18.x before 18.1.1. By making API requests involving nonexistent controllers, an authenticated user may cause the API worker to consume increasing amounts of memory, resulting in API performance degradation or denial of service.

CVE-2021-40797 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-2021-40797 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-40797
Security Fix Commit FIX COMMIT
https://github.com/openstack/neutron/commit/e610a5eb9e71aa2549fb11e2139370d227787da2
Neutron Source Repository REPOSITORY
https://github.com/openstack/neutron
Neutron Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/neutron/PYSEC-2021-329.yaml
launchpad.net/bugs/1942179 WEB
https://launchpad.net/bugs/1942179
Neutron Security Information SECURITY
https://security.openstack.org/ossa/OSSA-2021-006.html
Neutron Security Information SECURITY
http://www.openwall.com/lists/oss-security/2021/09/09/2

Frequently Asked Questions

What is CVE-2021-40797?
CVE-2021-40797 is a security vulnerability in Neutron involving OpenStack Neutron Denial of Service vulnerability under CWE-772: Missing Release of Resource after Effective Lifetime.
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-2021-40797?
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-2021-40797?
CVE-2021-40797 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:N/A:H.
What CWE is associated with CVE-2021-40797?
CVE-2021-40797 is classified under CWE-772: Missing Release of Resource after Effective Lifetime (The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.).
How can I check PyPI dependencies for CVE-2021-40797?
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-cpx3-696p-3cw9",
  "modified" : "2024-09-25T17:55:07Z",
  "published" : "2022-05-24T19:13:19Z",
  "aliases" : [ "CVE-2021-40797" ],
  "summary" : "OpenStack Neutron Denial of Service vulnerability",
  "details" : "An issue was discovered in the routes middleware in OpenStack Neutron before 16.4.1, 17.x before 17.2.1, and 18.x before 18.1.1. By making API requests involving nonexistent controllers, an authenticated user may cause the API worker to consume increasing amounts of memory, resulting in API performance degradation or denial of service.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/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-2021-40797"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/openstack/neutron/commit/e610a5eb9e71aa2549fb11e2139370d227787da2"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/openstack/neutron"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/neutron/PYSEC-2021-329.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://launchpad.net/bugs/1942179"
  }, {
    "type" : "WEB",
    "url" : "https://security.openstack.org/ossa/OSSA-2021-006.html"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2021/09/09/2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-772" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-02-23T21:39:51Z",
    "nvd_published_at" : "2021-09-08T20:15:00Z"
  }
}