CVE-2020-2509
CVE-2020-2509 is a security flaw in QNAP Network-Attached Storage (NAS), a network drive for storing files and backups at home or in a small office. Attackers can run their own code on QNAP Network-Attached Storage (NAS). The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 11 Apr 2022.[1]
QNAP Network-Attached Storage (NAS) is in things households have: network drives for files and backups, so the fix matters at home as much as at work. Fixed in version 4.5.2.1566 Build 20210202, 4.5.1.1495 Build 20201123, 4.3.6.1620 Build 20210322 and 4.3.4.1632 Build 20210324 and others.
Description
CISA calls it a network-attached storage (NAS) command injection in QNAP QNAP Network-Attached Storage (NAS). In its words: “QNAP NAS devices contain a command injection vulnerability which could allow attackers to perform remote code execution.”[1]
The CVE record adds: “A command injection vulnerability has been reported to affect QTS and QuTS hero. If exploited, this vulnerability allows attackers to execute arbitrary commands in a compromised application. We have already fixed this vulnerability in the following versions: QTS 4.5.2.1566 Build 20210202 and later QTS 4.5.1.1495 Build 20201123 and later QTS 4.3.6.1620 Build 20210322 and later QTS 4.3.4.1632 Build 20210324 and later QTS 4.3.3.1624 Build 20210416 and later QTS 4.2.6 Build 20210327 and later QuTS hero h4.5.1.1491 build 20201119 and later”[2]
The underlying weakness is command injection (CWE-77), OS command injection (CWE-78), 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 these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| QTS | 4.5.2.1566 Build 20210202 |
| QTS | 4.5.1.1495 Build 20201123 |
| QTS | 4.3.6.1620 Build 20210322 |
| QTS | 4.3.4.1632 Build 20210324 |
| QTS | 4.3.3.1624 Build 20210416 |
| QTS | 4.2.6 Build 20210327 |
| QuTS hero | h4.5.1.1491 build 20201119 |
Every device with QNAP Network-Attached Storage (NAS) needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 11 Apr 2022, 359 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 2 May 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 34%. That’s in the top 2% 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
QNAP has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Update QNAP Network-Attached Storage (NAS) now.Install the latest update from QNAP on every device that has it, and restart when asked. Then turn on automatic updates, so the next fix arrives on its own.
- Check you’re on 4.5.2.1566 Build 20210202 or later.Fixed in version 4.5.2.1566 Build 20210202, 4.5.1.1495 Build 20201123, 4.3.6.1620 Build 20210322 and 4.3.4.1632 Build 20210324 and others. Anything older is what attackers are going after.
- If the maker has stopped updating it, replace it.Network drives stop getting fixes after a few years, and attackers keep a list of the ones that did. If there’s no newer firmware, it won’t be fixed.
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 34%.[4] |
See also
Other QNAP flaws
- CVE-2023-47565, QNAP VioStor NVR: OS command injection ·
- CVE-2022-27593, QNAP Photo Station: externally controlled reference ·
- CVE-2019-7195, QNAP Photo Station: path traversal ·
- CVE-2019-7194, QNAP Photo Station: path traversal ·
- CVE-2019-7193, QNAP QTS: improper input validation ·
Other command injection flaws
- CVE-2026-105134, AhsayCBS: command injection ·
- CVE-2026-96951, Microsoft Windows: command injection ·
- CVE-2016-3081, Apache Struts: command injection ·
- CVE-2026-8037, Progress LoadMaster: command injection ·
- CVE-2025-29635, D-Link DIR-823X: command injection ·
Added the same day
- CVE-2022-23176, WatchGuard Firebox and XTM: privilege escalation ·
- CVE-2021-42287, Microsoft Active Directory: domain services privilege escalation ·
- CVE-2021-42278, Microsoft Active Directory: domain services privilege escalation ·
- CVE-2021-39793, Google Pixel: out-of-bounds write ·
- CVE-2021-27852, Checkbox Survey: survey deserialization of untrusted data ·
Every QNAP flaw on CISA’s list · Everything added in April 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “QNAP Network-Attached Storage (NAS) Command Injection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 11 Apr 2022.
- ^ National Institute of Standards and Technology. “CVE-2020-2509 Detail”. National Vulnerability Database, published 17 Apr 2021.
- ^ QNAP. Advisories and fixes: qnap.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.340, percentile 98.4, 31 Oct 2026.
- CVE Program. “CVE-2020-2509”. 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.