CVE-2020-13927
CVE-2020-13927 is a security flaw in Apache Airflow's Experimental API, open-source software from the Apache Software Foundation. Attackers can get into Apache Airflow's Experimental API without a valid password. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 18 Jan 2022.[1]
Apache Airflow's Experimental API is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed in version 1.10.11 of airflow.
Description
CISA calls it an authentication bypass in Apache Airflow's Experimental API. In its words: “The previous default setting for Airflow's Experimental API was to allow all API requests without authentication.”[1]
The CVE record adds: “The previous default setting for Airflow's Experimental API was to allow all API requests without authentication, but this poses security risks to users who miss this fact. From Airflow 1.10.11 the default has been changed to deny all requests by default and is documented at https://airflow.apache.org/docs/1.10.11/security.html#api-authentication. Note this change fixes it for new installs but existing users need to change their config to default `[api]auth_backend = airflow.api.auth.backend.deny_all` as mentioned in the Updating Guide: https://github.com/apache/airflow/blob/1.10.11/UPDATING.md#experimental-api-will-deny-all-request-by-default”[2]
The underlying weakness is CWE-1188, missing authentication (CWE-306), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| airflow | 1.10.11 |
Most families won’t have Apache Airflow's Experimental API; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 18 Jan 2022, 434 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 18 Jul 2022 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at over 99%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Apache has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Apache Airflow's Experimental API is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 1.10.11 of airflow), or not in use. CISA gave US government agencies until 18 Jul 2022 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at over 99%.[4] |
See also
Other Apache flaws
- CVE-2016-3081, Apache Struts: command injection ·
- CVE-2026-34486, Apache Tomcat: missing encryption of sensitive data ·
- CVE-2026-34197, Apache ActiveMQ: improper input validation ·
- CVE-2024-38475, Apache HTTP Server: improper escaping of output ·
- CVE-2025-24813, Apache Tomcat: path equivalence ·
Similar flaws
- CVE-2025-48927, TeleMessage TM SGNL: initialization of a resource with an insecure default ·
- CVE-2023-6448, Unitronics Vision PLC and HMI: insecure default password ·
Added the same day
- CVE-2021-40870, Aviatrix Controller: controller unrestricted upload of file ·
- CVE-2021-33766, Microsoft Exchange Server: information disclosure ·
- CVE-2021-32648, October CMS: improper authentication ·
- CVE-2021-25298, Nagios XI: XI OS command injection ·
- CVE-2021-25297, Nagios XI: XI OS command injection ·
Every Apache flaw on CISA’s list · Everything added in January 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Apache Airflow's Experimental API Authentication Bypass”. Known Exploited Vulnerabilities Catalog, added 18 Jan 2022.
- ^ National Institute of Standards and Technology. “CVE-2020-13927 Detail”. National Vulnerability Database, published 10 Nov 2020.
- ^ Apache. Advisories and fixes: lists.apache.org.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.998, percentile 100.0, 31 Oct 2026.
- CVE Program. “CVE-2020-13927”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.