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NVD / CVE Program· CNA apache

CVE-2021-38540: Apache Airflow: Variable Import endpoint missed authentication check

CriticalCVSS 9.8 · v3.1—Proof of concept Fix available

Noroxi assessment

Priority: This week (action score 63/100)

  • A ready-made attack module is public (Nuclei); exploiting it takes no special expertise.
  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 80.9% (FIRST EPSS); higher than 99.6% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: apache-airflow (PyPI) 2.1.3.

Don’t wait for the next maintenance window. Upgrade to apache-airflow (PyPI) 2.1.3 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

The variable import endpoint was not protected by authentication in Airflow >=2.0.0, <2.1.3. This allowed unauthenticated users to hit that endpoint to add/modify Airflow variables used in DAGs, potentially resulting in a denial of service, information disclosure or remote code execution. This issue affects Apache Airflow >=2.0.0, <2.1.3.

Published
Sep 9, 2021
Updated
Jun 17, 2026
EPSS
80.9% · 99th percentile

Report tools

JSON

Action score

63

This week

Don’t wait for the next maintenance window.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
24 / 30 · 80.9%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-38540

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
apacheairflow

Versions reported by the vendor

Affected version ranges reported by the assigning authority (apache). Independent of NVD's CPE analysis and usually ahead of it.

  • Apache Software Foundation Apache Airflow

    • Apache Airflow and later · before 2.1.3affected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • apache airflow2.0.0 and later · before 2.1.3

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
PyPIapache-airflowfrom 2.0.0 · before 2.1.32.1.3

Same product

apache: all records

Other highest-scoring records for the same primary product.

  • CVE-2020-13927The previous default setting for Airflow's Experimental API was to allow all API requests without authentication, but this poses security…KEV
    99Now
  • CVE-2020-11978An issue was found in Apache Airflow versions 1.10.10 and below.KEV
    95Now
  • CVE-2022-40127Apache Airflow <2.4.0 has an RCE in a bash example
    61This week

Published before and after this one in the same product

  • ← EarlierCVE-2021-28359May 2, 2021 · Apache Airflow Reflected XSS via Origin Query Argument in URL
    28Monitor
  • ← EarlierCVE-2021-35936Aug 16, 2021 · No Authentication on Logging Server
    23Monitor
  • Later →CVE-2021-45230Jan 20, 2022 · Apache Airflow: Creating DagRuns didn't respect Dag-level permissions in the Webserver
    27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
PyPI:apache-airflow2.1.3Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Nuclei detection template ×1
  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Nuclei detection templateNuclei template CVE-2021-38540 —
Proof-of-concept repository on GitHubstars:42022-06-13

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+277 d
  3. TodayNov 14, 2026+1892 d

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Not on record for this CVE: EPSS history · patch commit or PR link · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-269 · Improper Privilege Management

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

To simplify setup, a service account is granted broad, cluster-wide permissions. The principle of least privilege is skipped during installation.

The bug in code

The whole CWE-269 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

yaml
kind: ClusterRolerules:  - apiGroups: ["*"]    resources: ["*"]    verbs: ["*"]

Fixed

yaml
kind: Rolemetadata:  namespace: lodos-systemrules:  - apiGroups: ["apps"]    resources: ["deployments"]    verbs: ["get", "list", "update"]

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records