CriticalCVE-2025-66644

    Array Networks ArrayOS AG OS Command Injection Vulnerability (CVE-2025-66644)

    Published In CISA KEV since Sources: CVE.org, pwn.watch

    What is affected, what to do

    An attacker can execute arbitrary commands due to an OS command injection vulnerability in Array Networks ArrayOS AG versions prior to 9.4.5.9, leading to full system control. This vulnerability is actively exploited in the wild, notably in ransomware campaigns from August to December 2025. All versions before 9.4.5.9 are affected, and an immediate update to the latest version is urgently required to mitigate the risk.

    The vulnerability is being actively exploited; treat it as a priority. Update Array Networks ArrayOS to version 9.4.5.9. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Array Networks ArrayOS lt *..9.4.5.9
    Fixed in
    • Array Networks ArrayOS 9.4.5.9

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    9.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    7.2

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org, pwn.watch

    3.4 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 88.9

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    211.77 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: VulnCheck KEV (opens in a new tab) How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    9.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.2
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    3.4 %
    Moderate — model estimates 1-10% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    88.9
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-78

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw is network-reachable without authentication or user interaction and gives an attacker full control of a perimeter device, which is a prime foothold for moving into the internal network. According to the description, it was exploited for several months before a fix shipped, and the likelihood of exploitation is high. CISA does not currently flag ransomware use. Typical targets are organisations that use Array AG for remote access; public reporting points mainly to Asia, but European mid-market and critical-infrastructure operators are also exposed. Give every internet-facing instance top priority, with the patch and a compromise assessment completed within 24 hours. A confirmed exploitation should be treated as a reportable incident under NIS2.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Take inventory: List every Array Networks ArrayOS AG instance, including SSL VPN and secure access gateways, physical and virtual, and confirm its firmware version. Anything below 9.4.5.9 is vulnerable. Start with devices whose web portal is reachable from the internet.
      • Patch: Upgrade to ArrayOS AG 9.4.5.9 or later. Use your emergency change process rather than waiting for the next maintenance window.
      • Check for compromise before patching: Exploitation is documented from August through December 2025. Before you upgrade, capture a forensic snapshot: configuration, logs, a file listing of the web directories and running processes. Patching does not remove webshells or persistence that are already in place.
      • Rotate credentials: If compromise is suspected, rotate every secret stored on the appliance. That covers local admin accounts, LDAP/RADIUS/AD bind accounts, SAML certificates and TLS keys. Terminate all active VPN sessions.
      • Isolate if you cannot patch now: Restrict external access to the portal (typically TCP 443) to known source ranges, or take the appliance offline temporarily. The management interface should only ever be reachable from a dedicated admin network.
      • Disable unused features: Public CERT reporting (including JPCERT/CC) links exploitation to the "DesktopDirect" remote desktop feature. Disable it if it is not in use, and confirm the exact scope in the vendor advisory.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: Put the gateway in its own DMZ zone. Apply default-deny egress from the appliance itself, allowing only required destinations such as auth servers, NTP, DNS and syslog. This blocks reverse shells and second-stage payload downloads.
      • East-west control: From the VPN address pool and the appliance, permit only explicitly approved internal services. Route access to domain controllers (TCP 88/389/445/636) and admin protocols (RDP 3389, SSH 22, WinRM 5985/5986) through defined jump hosts only.
      • WAF/IPS in front of the portal: Block or alert on requests whose URI, query string or body contains shell metacharacters. These include ;, |, `, $( and &&, plus encoded forms such as %3B, %7C, %60 and %24%28. Enable your IPS vendor's CVE-2025-66644 signatures as soon as they are published.
      • IAM/least privilege: Enforce MFA on admin access to the appliance and limit it to named accounts. Give directory bind accounts read-only rights so that stolen credentials cannot be used to write to AD.
      • Off-box logging: Enforce syslog forwarding to your SIEM. A compromised appliance can tamper with its local logs, but not with copies stored elsewhere.

    3. Runbook step 3

      Detection rules

      • Web access logs (gateway, reverse proxy, WAF): Hunt for shell metacharacters or command fragments such as wget, curl, /bin/sh, bash -c, nc , chmod or base64 -d in URLs or parameters. Example SPL: index=proxy dest=<array_gw> (uri="*%3B*" OR uri="*%7C*" OR uri="*%60*" OR uri="*bash*" OR uri="*wget*")
      • Webshell indicators: Look for HTTP 200 responses on previously unseen paths under the portal's web directories, such as new .php or .cgi files, and for repeated POSTs to the same unusual resource. Diff the file listings against a known-good vendor baseline.
      • Network telemetry (Zeek/Suricata/firewall): Treat appliance-initiated connections to non-allowlisted internet hosts as high-severity, especially on ports like 4444, 8080 and 1337 or as long-lived sessions. Example KQL: CommonSecurityLog | where SourceIP == "<array_gw_ip>" and DestinationIP !in (allowlist) | summarize count() by DestinationIP, DestinationPort
      • Lateral movement from the VPN pool: Review Windows events 4624 (logon type 3/10) and 4625 sourced from VPN pool addresses. Also watch for 4768/4769 spikes on domain controllers and for Kerberos requests by the gateway's service accounts outside their normal patterns.
      • Configuration changes: Alert on new local admin accounts, changed auth sources or certificates, and reboots outside scheduled maintenance in the appliance audit log.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    Array Networks ArrayOS AG before 9.4.5.9 allows command injection, as exploited in the wild in August through December 2025.

    Source: NVD (NIST), cvelistv5, CISA KEV Catalog, CVE.org (MITRE), pwn.watch

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    Array NetworksArrayOS AG
    • < 9.4.5.9
    • 9.4.5.9

    Vendors and products

    Affected operating systems

    Affected operating systems
    Otherarraynetworksarrayos_ag—

    Weakness classes (CWE)

    • CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

      Base

      The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

      Entry at MITRE CWE-78

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited

    References & sources

    • JPCERT/CCArray Networks advisory: Array Networks ArrayOS AGThird-party advisory, pwn-watch
    • x.comArraySupport/status/1921373397533032590Third-party advisory
    • bleepingcomputer.comnews/security/hackers-are-exploiting-arrayos-ag-vpn-flaw-to-pla…Press coverage
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2025-66644government-resource, US government resource
    • pwn.watchpwn.watch: Array Networks ArrayOS AG: ArrayOS AG OS Command Injection Vulnerabilitypwn-watch
    • support.arraynetworks.netArray Networks advisory: Array Networks ArrayOS AGpwn-watch
    • NVD (NIST)NVD: CVE-2025-66644pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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