CriticalCVE-2021-44529

    Ivanti Endpoint Manager Cloud Service Appliance (EPM CSA) Code Injection Vulnerability (CVE-2021-44529)

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

    What is affected, what to do

    The vulnerability CVE-2021-44529 allows an attacker to execute arbitrary code with limited permissions via a code injection flaw in the Ivanti Endpoint Manager Cloud Service Appliance (EPM CSA) without authentication. It is actively exploited in ransomware campaigns since 2021. Affected products include version 4.5 of the Ivanti EPM Cloud Services Appliance. Organizations should urgently patch to the latest version to mitigate this risk.

    The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. 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
    • Ivanti EPM eq 4.6.0-512..4.6.0-512

    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

    99.10 %

    EPSS score

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

    Source: FIRST EPSS, percentile 99.93

    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
    254.04 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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    99.10 %
    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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    99.93
    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
    CISA assessment (SSVC)
    Exploitation: active · automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 31 March 2022
    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-94

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This flaw is network-reachable without authentication or user interaction, public exploit code has circulated for years, and it sits among the CVEs most likely to be exploited at all. CISA also flags known use in ransomware campaigns. The CSA is internet-facing by design as the gateway for endpoint management, which makes it an ideal initial-access point: after escalating privileges, attackers can abuse the management plane to push payloads across the fleet. Treat any internet-reachable CSA 4.5 as critical, with immediate containment and a compromise assessment. Only internal-only, segmented instances can follow the regular patch cycle within a few days.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory: Enumerate every Ivanti EPM Cloud Services Appliance (CSA), especially version 4.5 and earlier. Confirm whether its web interface (typically TCP/443) is reachable from the internet by checking your ranges in Shodan/Censys and reviewing firewall NAT rules.
      • Patch or migrate: Apply the vendor fix for CVE-2021-44529. A patch is available from the vendor — look up the exact version in the Ivanti advisory. CSA 4.5 is legacy, so if you cannot move to a supported release, decommission the appliance.
      • Cut exposure now: Until patched, restrict internet access to the CSA to known source ranges (managed clients, partner VPN) or unpublish it temporarily. Accept the outage of remote client management.
      • Check for compromise before patching: Preserve a forensic image or snapshot of the appliance, including web server logs, /tmp, the webroot and crontabs. Patching does not remove webshells or persistence that are already in place.
      • Rotate credentials: If compromise is suspected, rotate every secret stored on or brokered through the CSA: EPM core binding, service accounts, certificates and local admin passwords. Initial execution runs as nobody, but privilege escalation on an outdated appliance is a realistic follow-on.
      • Reporting: If exploitation is confirmed, keep the NIS2 24-hour early-warning deadline in mind. The CSA is a management gateway with a direct path into the internal network.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: Place the CSA in a dedicated DMZ zone. Allow outbound traffic only to the EPM core server and required Ivanti services. Block all other egress, particularly arbitrary HTTP/S, DNS tunnelling and common reverse-shell ports.
      • East-west control: Limit CSA-to-internal traffic to the required core ports. Block SMB, RDP, SSH and LDAP from the appliance towards clients and domain controllers to hinder lateral movement.
      • WAF/IPS: Front the appliance with a reverse proxy or WAF. Block requests to CSA PHP endpoints (e.g. under /client/) that carry abnormally long or Base64-looking cookie or header values, since public PoCs deliver the payload this way. Enable vendor IPS signatures for CVE-2021-44529 and update your Suricata ET and Snort rulesets.
      • Access restriction: Allow administrative access only via MFA-protected VPN or from an admin jump-host network, never directly from the internet.
      • System hardening: Check whether the nobody web user can write to the webroot, /tmp or /var/tmp. Where possible, mount temp directories noexec and monitor webroot integrity with file integrity monitoring (AIDE/Tripwire-style).
      • Lifecycle: If migration cannot happen quickly, record the appliance as a legacy asset in the risk register (ISO 27001 A.8.8). Obtain a time-boxed, management-signed risk acceptance and set a hard decommission date.

    3. Runbook step 3

      Detection rules

      • Web access logs (Apache on the CSA or upstream proxy): Hunt for requests to /client/*.php with unusually long or Base64-like cookie or header values that return HTTP 200 to unfamiliar source IPs. SPL: index=proxy uri_path="/client/*" | eval clen=len(cookie) | where clen>200 | stats count by src_ip, uri_path
      • Process ancestry (EDR/auditd where available): Treat any child process of the web server or PHP interpreter running as nobody as high-fidelity: sh, bash, curl, wget, nc, python, perl. auditd: -a always,exit -F arch=b64 -S execve -F uid=nobody -k csa_nobody_exec. Escalate any hit whose comm is outside the normal PHP runtime.
      • Filesystem: Look for new or modified .php files in the webroot, executables dropped in /tmp or /var/tmp, and new crontab entries for nobody. Sigma shape: logsource: linux/file_event; selection: TargetFilename|endswith: '.php' AND User: 'nobody'.
      • Network telemetry (Zeek/Suricata/firewall): Flag CSA outbound connections to destinations outside the allow-list, especially new external IPs, odd ports, or downloads from paste or file-hosting sites. Zeek: filter conn.log on id.orig_h == <CSA-IP> where id.resp_h is not allow-listed.
      • Lateral movement: Watch for logons from the CSA IP to internal Windows hosts (Event ID 4624 with logon type 3/10, and 4648) and for Kerberos requests (4768/4769) originating from the appliance. A CSA does not normally authenticate interactively to endpoints.

    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

    A code injection vulnerability in the Ivanti EPM Cloud Services Appliance (CSA) allows an unauthenticated user to execute arbitrary code with limited permissions (nobody).

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

    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
    —Ivanti EPM
    • 4.6.0-512
    • —
    ivantiendpoint_manager_cloud_services_appliance
    • ≤ 4.5
    • 4.6
    • —
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-94Improper Control of Generation of Code ('Code Injection')

      Base

      The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

      Entry at MITRE CWE-94

    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 StormIvanti Endpoint Manager CSA 4.5 4.6 Remote Code Execution (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—
    Packet StormIvanti Cloud Services Appliance CSA Command Injection (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—

    References & sources

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