NewsCompaniesFlawsGuides
Get the app

CVE-2025-66644

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in Array Networks ArrayOS AG. For every flaw being used in attacks, see Exploited flaws.

CVE-2025-66644 is a security flaw in Array Networks ArrayOS AG. Attackers can run commands on Array Networks ArrayOS AG. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 8 Dec 2025.[1]

Array Networks ArrayOS AG 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 9.4.5.9 of ArrayOS AG.

Description

CISA calls it an OS command injection in Array Networks ArrayOS AG. In its words: “Array Networks ArrayOS AG contains an OS command injection vulnerability that could allow an attacker to execute arbitrary commands.”[1]

The underlying weakness is OS command injection (CWE-78), in MITRE’s list of common software weaknesses.[2]

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]

ProductFixed in
ArrayOS AG9.4.5.9

Most families won’t have Array Networks ArrayOS AG; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 8 Dec 2025, 3 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 29 Dec 2025 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 3%. That’s in the top 12% 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

Array Networks has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]

  1. Check whether you use it.Array Networks ArrayOS AG 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.
  2. Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 9.4.5.9 of ArrayOS AG), or not in use. CISA gave US government agencies until 29 Dec 2025 to fix it.
  3. 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

DateEvent
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 3%.[4]

See also

Other Array Networks flaws

  • CVE-2023-28461, Array Networks AG/vxAG ArrayOS: AG and vxAG arrayOS missing authentication for critical function ·

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

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “Array Networks ArrayOS AG OS Command Injection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 8 Dec 2025.
  2. ^ National Institute of Standards and Technology. “CVE-2025-66644 Detail”. National Vulnerability Database, published 5 Dec 2025.
  3. ^ Array Networks. Advisories and fixes: support.arraynetworks.net, jpcert.or.jp.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.034, percentile 88.9, 31 Oct 2026.
  5. CVE Program. “CVE-2025-66644”. 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.