CVE-2021-26697: Apache airflow Improper Authentication Vulnerability

MODERATE
Advisory Identifier: GHSA-fh37-cx83-q542
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CVSS 5.3
CWE-287 CWE-269 CWE-306
Published
Advisory Summary

CVE-2021-26697 is a MODERATE (CVSS 5.3) improper authentication vulnerability (CWE-287: Improper Authentication) affecting Apache airflow libraries in the PyPI ecosystem. The issue involves improper authentication in apache airflow. Remediation is available by upgrading affected packages to version 2.0.1rc1.

CVE-2021-26697 at a Glance

CVE Identifier CVE-2021-26697
GHSA Identifier GHSA-fh37-cx83-q542
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-287: Improper Authentication
Affected Product Apache airflow
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 5.3

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

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

How to Fix CVE-2021-26697

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

apache-airflow fixed: 2.0.1rc1 
pip install apache-airflow>=2.0.1rc1
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 apache-airflow

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2021-26697, inspect your installed packages using pip:

pip show apache-airflow

Analyze the terminal output to locate any version of Apache airflow in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.0.1rc1), your application is affected.

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

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-287: Improper Authentication, where when an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. In Apache airflow, 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

The lineage endpoint of the deprecated Experimental API was not protected by authentication in Airflow 2.0.0. This allowed unauthenticated users to hit that endpoint. This is low-severity issue as the attacker needs to be aware of certain parameters to pass to that endpoint and even after can just get some metadata about a DAG and a Task. This issue only affects Apache Airflow 2.0.0.

CVE-2021-26697 Affected Apache airflow Versions

1 component(s)
Fixed Versions:
2.0.1rc1
Product / Package Ecosystem Affected Versions Fixed Version
apache-airflow
pypi/apache-airflow
PyPI
≥ 2.0.0
< 2.0.1rc1
All 1 versions
2.0.0
2.0.1rc1

References

NVD — CVE-2021-26697 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-26697
Security Fix Commit FIX COMMIT
https://github.com/apache/airflow/commit/21cedff205e7d62675949fda2aa4616d77232b76
Security Fix Commit FIX COMMIT
https://github.com/apache/airflow/commit/24a54242d56058846c7978130b3f37ca045d5142
Security Fix Commit FIX COMMIT
https://github.com/apache/airflow/commit/93957e917ff4cfb0be11aef088bd9527cf728a04
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-fh37-cx83-q542
Apache airflow Source Repository REPOSITORY
https://github.com/apache/airflow
Apache airflow Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/apache-airflow/PYSEC-2021-3.yaml
lists.apache.org/thread.html/r361112... WEB
https://lists.apache.org/thread.html/r36111262a59219a3e2704c71e97cf84937dae5ba7a1da99499e5d8f9@%3Cannounce.apache.org%3E
lists.apache.org/thread.html/re21fec... WEB
https://lists.apache.org/thread.html/re21fec81baea7a6d73b0b5d31efd07cc02c61f832e297f65bb19b519%40%3Cusers.airflow.apache.org%3E
lists.apache.org/thread.html/re21fec... WEB
https://lists.apache.org/thread.html/re21fec81baea7a6d73b0b5d31efd07cc02c61f832e297f65bb19b519@%3Cdev.airflow.apache.org%3E
lists.apache.org/thread.html/re21fec... WEB
https://lists.apache.org/thread.html/re21fec81baea7a6d73b0b5d31efd07cc02c61f832e297f65bb19b519@%3Cusers.airflow.apache.org%3E
Apache airflow Security Information SECURITY
http://www.openwall.com/lists/oss-security/2021/02/17/2

Frequently Asked Questions

What is CVE-2021-26697?
CVE-2021-26697 is a security vulnerability in Apache airflow involving Improper Authentication in Apache Airflow under CWE-287: Improper Authentication.
Which Apache airflow versions are affected?
Affected versions include releases prior to 2.0.1rc1 across affected packages: apache-airflow.
What version fixes CVE-2021-26697?
Upgrading to 2.0.1rc1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is apache-airflow affected?
Yes, apache-airflow is affected in releases prior to 2.0.1rc1. Upgrade your dependency to 2.0.1rc1 or later.
What is the CVSS score of CVE-2021-26697?
CVE-2021-26697 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2021-26697?
CVE-2021-26697 is classified under CWE-287: Improper Authentication (When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.).
How can I check PyPI dependencies for CVE-2021-26697?
Run the dependency tree command: 'pip show apache-airflow'. 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-fh37-cx83-q542",
  "modified" : "2024-09-12T20:10:22Z",
  "published" : "2021-06-18T18:30:11Z",
  "aliases" : [ "CVE-2021-26697" ],
  "summary" : "Improper Authentication in Apache Airflow",
  "details" : "The lineage endpoint of the deprecated Experimental API was not protected by authentication in Airflow 2.0.0. This allowed unauthenticated users to hit that endpoint. This is low-severity issue as the attacker needs to be aware of certain parameters to pass to that endpoint and even after can just get some metadata about a DAG and a Task. This issue only affects Apache Airflow 2.0.0.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "apache-airflow"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.0.1rc1"
      } ]
    } ],
    "versions" : [ "2.0.0" ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-26697"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apache/airflow/commit/21cedff205e7d62675949fda2aa4616d77232b76"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apache/airflow/commit/24a54242d56058846c7978130b3f37ca045d5142"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apache/airflow/commit/93957e917ff4cfb0be11aef088bd9527cf728a04"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-fh37-cx83-q542"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/apache/airflow"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/apache-airflow/PYSEC-2021-3.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/r36111262a59219a3e2704c71e97cf84937dae5ba7a1da99499e5d8f9@%3Cannounce.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/re21fec81baea7a6d73b0b5d31efd07cc02c61f832e297f65bb19b519%40%3Cusers.airflow.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/re21fec81baea7a6d73b0b5d31efd07cc02c61f832e297f65bb19b519@%3Cdev.airflow.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/re21fec81baea7a6d73b0b5d31efd07cc02c61f832e297f65bb19b519@%3Cusers.airflow.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2021/02/17/2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-269", "CWE-287", "CWE-306" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-07T21:48:45Z",
    "nvd_published_at" : "2021-02-17T15:15:00Z"
  }
}