CVE-2021-38540

CRITICALNVD 9.89.8—
EchelonGraph scoreHIGH confidence

Score elevated to 9.8 because EPSS predicts 92% probability of exploitation within the next 30 days (top 0.3% of all CVEs). NVD baseline CVSS 9.8 retained for reference. Confidence: see factors.

Triggered by: EPSS exploit prediction ≥85%
Sources: epss, nvd
Elevated
9.8
EchelonGraph verdictPatch this weekExploitation is likely or a public exploit exists.
  • High exploitation likelihood — EPSS 81%
CISA-KEV: Not listedEPSS: 81%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
9.8
EG Score
9.8(high)
EPSS
99.6%
KEV
Not listed

Published

September 9, 2021

Last Modified

November 21, 2024

Advisory Details (2)

Auto-updated Jun 21, 2026
No patch confirmed yet.
generic
https://lists.apache.org/thread.html/rb34c3dd1a815456355217eef34060789f771b6f77c3a3dec77de2064%40%3Cusers.airflow.apache.org%3E
generic
https://lists.apache.org/thread.html/rac2ed9118f64733e47b4f1e82ddc8c8020774698f13328ca742b03a2%40%3Cannounce.apache.org%3E

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
apache-airflow2.0.0 ... 2.1.3rc1 (14 versions)2.1.3—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 6× in last 7d / 20× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:06 UTCEPSS rescore
  2. 2026-07-22 14:06 UTCEPSS rescore
  3. 2026-07-20 17:05 UTCEPSS rescore
  4. 2026-07-18 12:29 UTCOSV refresh
  5. 2026-07-16 17:00 UTCEPSS rescore
  6. 2026-07-16 17:00 UTCEPSS rescore
  7. 2026-07-15 16:55 UTCEPSS rescore
  8. 2026-07-15 01:58 UTCEPSS rescore
  9. 2026-07-11 08:25 UTCEPSS rescore
  10. 2026-07-11 08:25 UTCEPSS rescore
  11. 2026-07-09 19:07 UTCEPSS rescore
  12. 2026-07-06 02:21 UTCEPSS rescore
  13. 2026-06-30 23:20 UTCEPSS rescore
  14. 2026-06-30 23:20 UTCEPSS rescore
  15. 2026-06-30 15:00 UTCOSV refresh
  16. 2026-06-27 03:06 UTCEPSS rescore
  17. 2026-06-25 13:48 UTCEPSS rescore
  18. 2026-06-25 13:48 UTCEPSS rescore
  19. 2026-06-23 21:31 UTCEPSS rescore
  20. 2026-06-23 21:31 UTCEPSS rescore
  21. 2026-06-21 01:58 UTCEPSS rescore
  22. 2026-06-21 01:58 UTCEPSS rescore
  23. 2026-06-17 17:51 UTCEPSS rescore
  24. 2026-06-16 17:51 UTCEPSS rescore
  25. 2026-06-16 17:51 UTCEPSS rescore
Show 17 more
  1. 2026-06-15 17:46 UTCEPSS rescore
  2. 2026-06-12 22:10 UTCOSV refresh
  3. 2026-06-11 13:58 UTCEPSS rescore
  4. 2026-06-10 22:16 UTCEPSS rescore
  5. 2026-06-10 13:20 UTCEPSS rescore
  6. 2026-06-07 15:23 UTCEPSS rescore
  7. 2026-06-07 15:23 UTCEPSS rescore
  8. 2026-06-06 13:46 UTCEPSS rescore
  9. 2026-06-06 13:46 UTCEPSS rescore
  10. 2026-06-06 13:46 UTCEPSS rescore
  11. 2026-06-05 22:45 UTCEPSS rescore
  12. 2026-05-28 13:43 UTCEPSS rescore
  13. 2026-05-28 13:43 UTCEPSS rescore
  14. 2026-05-27 13:39 UTCEPSS rescore
  15. 2026-05-27 13:39 UTCEPSS rescore
  16. 2026-05-27 13:39 UTCEPSS rescore
  17. 2026-05-26 10:39 UTCEG score recompute

Publicly available exploits

(2 references)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCCaptain-v-hook/PoC-for-CVE-2021-38540-
    First seen Jun 13, 2022

    Missing Authentication on Critical component CVE-2021-38540

    Open source ↗
  • Nucleihttp/cves/2021/CVE-2021-38540.yaml
    First seen Jan 1, 2021

    Apache Airflow - Unauthenticated Variable Import

    Open source ↗

Frequently asked(5)

What is CVE-2021-38540?
CVE-2021-38540 is a critical vulnerability published on September 9, 2021. 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…
When was CVE-2021-38540 disclosed?
CVE-2021-38540 was first published in the National Vulnerability Database on September 9, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-38540 actively exploited?
CVE-2021-38540 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-38540?
CVE-2021-38540 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2021-38540?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-38540, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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