CriticalCVE-2019-7256

    Nice Linear eMerge E3-Series OS Command Injection Vulnerability (CVE-2019-7256)

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

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    What is affected, what to do

    Linear eMerge E3-Series devices allow Command Injections.

    The vulnerability is being actively exploited; treat it as a priority. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Nortek Control Linear eMerge Essential Firmware lte *..1.00-06
    • Nortek Control Linear eMerge Elite Firmware lte *..1.00-06

    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

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: pwn.watch, CVE.org

    97.1 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.89

    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
    228.82 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.

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    actively exploited
    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.

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    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
    9.8
    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“.

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    97.1 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    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.

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    99.89
    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.

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    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
    CISA assessment (SSVC)
    Exploitation: active · automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 27 March 2024
    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 CVE sits on KEV because it has been actively and broadly abused by botnet operators (Mirai derivatives among them) since 2019 — the device is network-reachable without authentication and yields direct remote code execution with root-equivalent privileges on an access-control panel. Exploitation likelihood is among the highest across the entire CVE corpus. For NIS2-scoped organisations the risk is sharper when eMerge panels gate physical access to data centres, production sites or KRITIS facilities: a compromised panel means not just botnet infection but potential bypass of physical security controls. Rate P1 if even one device is externally reachable or sits on a flat network with office IT; drop to P2 only where the device is fully segmented and offline, paired with a hardware replacement roadmap.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Pull every Nice/Linear eMerge E3-Series access controller (Elite and Essential, firmware 1.00-06 and older) off the public internet immediately. Perimeter firewall rule: drop inbound TCP/80 and TCP/443 to these devices; cross-check your own public IP ranges in Shodan/Censys for the "eMerge" banner.
      • Check Nortek Control / Nice for an updated firmware — a publicly confirmed, fully patched release for this CVE has not been available for years. If no patch exists, move to isolation; otherwise deploy the current vendor firmware (version per vendor advisory).
      • Rotate default credentials (admin/admin) and all known service accounts on every eMerge panel; review the last 90 days of HTTP Basic Auth logs for unknown logins.
      • Relocate affected devices into a dedicated OT / building-systems VLAN with no outbound internet connectivity; permit management only via jump host with MFA.
      • Open a Critical-severity incident ticket and start forensic triage: search HTTP access logs for the web interface endpoints (/badging/, /card_scan.php, /card_scan_decoder.php, /forgot_password.php) for shell metacharacters (;, |, `, $() in query parameters.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: isolate eMerge controllers in a dedicated access-control VLAN; strict firewall ACL — only the access-control server and the admin jump host may initiate TCP/80, TCP/443; drop and log everything else.
      • Front the devices with a reverse proxy or WAF (nginx, HAProxy, F5): URL filter on /card_scan_decoder.php, /card_scan.php, /forgot_password.php plus request-body inspection for shell metacharacters and typical payload fragments (wget , curl , /tmp/, |sh, ;id).
      • Enforce default-deny egress on controllers. Explicitly block outbound HTTP/HTTPS/DNS to arbitrary destinations to kill the classic Mirai-style second-stage pull via wget http://.../bins/….
      • Enable IDS/IPS signatures: Suricata/Snort rules for CVE-2019-7256 (ET Pro set and Emerging Threats "eMerge" / "Nortek") in blocking mode; add a generic rule against card_scan_decoder.php with No= parameter plus shell metacharacters.
      • Document and rehearse physical fallback procedures for building access in case the panel must be shut down pre-emptively — loop in facility management and security guards.
      • Audit CMDB for asset end-of-life status; schedule replacement with a currently supported platform in the 2025/2026 capex plan.

    3. Runbook step 3

      Detection rules

      • Web access log pattern (Zeek http.log, nginx, Apache): uri containing card_scan_decoder.php, card_scan.php or forgot_password.php combined with URL-encoded shell metacharacters (%3B, %7C, %60, %24%28). Sigma shape: selection.cs-uri-query|contains: ['%3B','%7C','','$(']`.
      • Network telemetry: outbound HTTP GET from the eMerge controller to any non-management IP — treat as suspicious by default. Suricata: alert http $EMERGE_NET any -> !$INTERNAL any (msg:"eMerge egress HTTP"; sid:...).
      • DNS logs: queries from the controller IP to low-reputation domains or Pastebin/GitHub raw hosts — indicator of second-stage tooling download.
      • EDR/host (if an agent is feasible, or via device syslog): new processes under the web server user (lighttpd, www-data) such as sh, wget, curl, nc, busybox — the process ancestry webserver → shell → download tool is the signature path for this CVE.
      • SIEM baseline: volume and source-IP diversity of HTTP requests against the admin interface — a sudden spike from atypical ASNs (hosting providers, VPS) should trigger an alert.

    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

    Linear eMerge E3-Series devices allow Command Injections.

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

    Vendors and products

    Affected operating systems

    Affected operating systems
    Othernortekcontrollinear_emerge_elite_firmware—
    Othernortekcontrollinear_emerge_essential_firmware—

    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
    Packet StormLinear eMerge E3 1.00 06 card_scan.php Command Injection (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—
    Packet StormLinear eMerge E3 1.00 06 card_scan_decoder.php Command Injection (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—
    Packet StormLinear eMerge E3 Access Controller Command Injection (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—
    Packet StormLinear eMerge E3 Series Access Controller Command Injection (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—

    References & sources

    • applied-risk.comlabs/advisoriesNot applicable
    • applied-risk.comresources/ar-2019-005Third-party advisory
    • packetstormsecurity.comfiles/155255/Linear-eMerge-E3-1.00-06-card_scan.php-Command-Inj…Exploit, Third-party advisory, Vulnerability database
    • packetstormsecurity.comfiles/155256/Linear-eMerge-E3-1.00-06-card_scan_decoder.php-Com…Exploit, Third-party advisory, Vulnerability database
    • packetstormsecurity.comfiles/155272/Linear-eMerge-E3-Access-Controller-Command-Injecti…Exploit, Third-party advisory, Vulnerability database
    • packetstormsecurity.comfiles/170372/Linear-eMerge-E3-Series-Access-Controller-Command-…Exploit, Third-party advisory, Vulnerability database
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2019-7256government-resource, US government resource
    • pwn.watchpwn.watch: Nice Linear eMerge E3-Series OS Command Injectionpwn-watch
    • linear-solutions.comNice advisory: CVE-2019-7256pwn-watch
    • cisa.govNice advisory: CVE-2019-7256pwn-watch
    • NVD (NIST)NVD: CVE-2019-7256pwn-watch
    • cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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