CVE-2020-1956
CVE-2020-1956 is a security flaw in Apache Kylin, open-source software from the Apache Software Foundation. Attackers can run their own code on Apache Kylin. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 25 Mar 2022.[1]
Apache Kylin 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. Apache has published a fix or advice.
Description
CISA calls it an OS command injection in Apache Kylin. In its words: “Apache Kylin contains an OS command injection vulnerability which could permit an attacker to perform remote code execution.”[1]
The CVE record adds: “Apache Kylin 2.3.0, and releases up to 2.6.5 and 3.0.1 has some restful apis which will concatenate os command with the user input string, a user is likely to be able to execute any os command without any protection or validation.”[2]
The underlying weakness is OS command injection (CWE-78), in MITRE’s list of common software weaknesses.
It scores 8.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Apache’s advisory has them[3]. CISA names the product as Apache Kylin.
Most families won’t have Apache Kylin; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 25 Mar 2022, 672 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 15 Apr 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 97%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
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 Kylin 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, or not in use. CISA gave US government agencies until 15 Apr 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 8.8.[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 97%.[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 ·
Other OS command injection flaws
- CVE-2026-110447, Collabora Online – Built-in CODE Server: online – built-in CODE server OS command injection ·
- CVE-2026-106931, EG Secure Solutions SiteGuard Server Edition: OS command injection ·
- CVE-2026-83549, SonicWall SMA1000 Appliances: OS command injection ·
- CVE-2026-49869, Kestra OSS: OSS OS command injection ·
- CVE-2026-73570, Synacor Zimbra Collaboration Suite (ZCS): OS command injection ·
Added the same day
- CVE-2022-26318, WatchGuard Firebox and XTM Appliances: arbitrary code execution ·
- CVE-2022-26143, Mitel MiCollab, MiVoice Business Express: access control ·
- CVE-2022-21999, Microsoft Windows: print spooler privilege escalation ·
- CVE-2021-42237, Sitecore XP: remote command execution ·
- CVE-2021-22941, Citrix ShareFile: improper access control ·
Every Apache flaw on CISA’s list · Everything added in March 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Apache Kylin OS Command Injection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 25 Mar 2022.
- ^ National Institute of Standards and Technology. “CVE-2020-1956 Detail”. National Vulnerability Database, published 22 May 2020.
- ^ Apache. Advisories and fixes: lists.apache.org, lists.apache.org, lists.apache.org.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.974, percentile 99.9, 31 Oct 2026.
- CVE Program. “CVE-2020-1956”. 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.