CVE-2026-79806

Executive Summary

CVE-2026-79806 is a local privilege escalation vulnerability in the ClearPass Policy Manager OnGuard Linux agent, affecting systems where the agent is installed. A malicious user with existing local access to a Linux instance can exploit this flaw to elevate privileges to root. The vulnerability requires local access and low privileges (CVSS 7.8, AV:L/PR:L), but successful exploitation results in full system compromise with high impact to confidentiality, integrity, and availability.

Technical Analysis

The vulnerability resides in the ClearPass Policy Manager OnGuard Linux agent — a component used for endpoint posture assessment and network access control in Aruba (HPE) environments. The core issue is a privilege escalation flaw that allows a local, unprivileged user to obtain root-level permissions on the affected Linux client. The CVSS vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) indicates that the attack is local, requires low complexity, needs low privileges, and requires no user interaction. The scope remains unchanged, meaning the compromise impacts only the vulnerable component's security context — though in practice, root escalation on the endpoint grants full control over the host.

The NVD description does not specify the exact code-level mechanism (e.g., improper setuid handling, insecure file permissions, race condition, or command injection), and no CWE is provided. As a result, the precise technical root cause cannot be confirmed from available data. However, local privilege escalation in endpoint agents commonly stems from: insecure temporary file handling, misconfigured setuid binaries or systemd services, or improper privilege separation between the agent's service components and user-accessible interfaces. The OnGuard agent typically runs as a privileged background process and interacts with endpoint posture data; any weakness in how it validates or executes user-controlled input could allow a local attacker to hijack its elevated context. The attack surface is the local Linux instance where the agent is installed — no remote vector is indicated.

Exploitation Scenarios

Based exclusively on the NVD description and provided data, the attack chain is as follows:

1. Reconnaissance/target identification: An attacker gains an initial foothold on a Linux endpoint as a low-privileged user. This could occur via compromised credentials, a separate remote vulnerability, or insider access. The attacker identifies that the ClearPass Policy Manager OnGuard Linux agent is installed on the system.

2. Triggering the flaw class: The privilege escalation flaw class is exploited. Based on the CVSS vector (local, low complexity, low privileges, no user interaction), the attacker leverages the agent's misconfigured privileges — for example, by interacting with a vulnerable local interface, service, or executable associated with the agent. No specific function names, file paths, or parameters are provided in the NVD description, so the exact trigger cannot be detailed without fabrication.

3. Payload/execution method (vulnerability-class level): The attacker executes a local action that causes the agent to perform an operation with elevated privileges. This could involve invoking a binary, manipulating a file, or sending input to a service. The outcome is that the attacker's code or commands run in a root security context.

4. Post-exploitation impact: Successful exploitation yields root privileges on the affected Linux client. The attacker can then disable security controls, install persistence, exfiltrate sensitive data, pivot to other systems, or tamper with the ClearPass OnGuard agent itself to bypass network access control policies.

No public PoC or exploit code is available. The attack chain is inferred from the vulnerability class (local privilege escalation) and the CVSS vector. Specific implementation details are not present in the source data.

Impact Assessment

The impact of CVE-2026-79806 is severe for affected systems. The CVSS score of 7.8 reflects high confidentiality, integrity, and availability impacts. A local attacker who successfully escalates to root can:

• Read, modify, or delete any file on the system, including sensitive configuration and credential stores.
• Disable or manipulate the ClearPass OnGuard agent, potentially bypassing network access control and endpoint compliance checks.
• Install persistent malware, backdoors, or rootkits.
• Use the compromised host as a pivot point for lateral movement within the enterprise network.

The blast radius includes any Linux endpoint with the vulnerable OnGuard agent installed. Because ClearPass is used for network access control, compromise of the agent could undermine the entire NAC enforcement model. The EPSS score is not yet available, and the CVE is not listed in CISA KEV. No known active exploitation has been reported. However, the lack of a patch increases risk for organizations relying on the agent for compliance enforcement.

Detection Guidance

Sigma Rule

title: Local Privilege Escalation via ClearPass OnGuard Linux Agent
id: 8f7c2b1a-4d3e-4f5a-9b6c-7d8e9f0a1b2c
status: experimental
description: Detects suspicious process execution indicative of privilege escalation attempts targeting the ClearPass Policy Manager OnGuard Linux agent.
author: Threat Intelligence
date: 2026/01/01
logsource:
  category: process_creation
  product: linux
detection:
  selection_parent:
    ParentImage|endswith:
      - '/onguard'
      - '/OnGuard'
      - '/clearpass'
      - '/ClearPass'
  selection_child:
    Image|endswith:
      - '/sh'
      - '/bash'
      - '/python'
      - '/perl'
      - '/nc'
      - '/ncat'
    User|contains: 'root'
  condition: selection_parent and selection_child
falsepositives:
  - Legitimate administrative scripts
level: high
tags:
  - attack.t1068
  - attack.privilege_escalation

YARA Rule

rule CVE_2026_79806_ClearPass_OnGuard_PrivEsc
{
    meta:
        description = "Detects potential exploitation artifacts of CVE-2026-79806 in ClearPass OnGuard Linux agent"
        author = "Threat Intelligence"
        date = "2026-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-79806"
        severity = "high"
    strings:
        $s1 = "ClearPass" ascii wide nocase
        $s2 = "OnGuard" ascii wide nocase
        $s3 = "setuid" ascii wide nocase
        $s4 = "setgid" ascii wide nocase
        $s5 = "/tmp/" ascii wide
        $s6 = "root" ascii wide nocase
        $s7 = "chmod 4755" ascii wide nocase
        $s8 = "chown root" ascii wide nocase
    condition:
        (uint32(0) == 0x464c457f) and  // ELF file magic
        (2 of ($s1, $s2)) and
        (2 of ($s3, $s4, $s5, $s6, $s7, $s8))
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"CVE-2026-79806 ClearPass OnGuard Privilege Escalation Attempt - Local Exploit Staging"; flow:to_server,established; content:"ClearPass"; nocase; content:"OnGuard"; nocase; content:"/tmp/"; distance:0; content:"chmod"; nocase; distance:0; classtype:attempted-admin; sid:10000001; rev:1; reference:cve,2026-79806;)

Elastic Detection

process where process.parent.name in ("onguard", "OnGuard", "clearpass-agent", "ClearPass") and process.name in ("sh", "bash", "python", "perl", "nc", "ncat") and process.user.name == "root"

Splunk SPL Query

index=linux sourcetype=auditd OR sourcetype=syslog
(process_name=onguard OR process_name=OnGuard OR process_name=clearpass* OR parent_process_name=onguard OR parent_process_name=OnGuard)
AND (process_name=sh OR process_name=bash OR process_name=python OR process_name=perl OR process_name=nc OR process_name=ncat)
AND user=root
| stats count by host, user, process_name, parent_process_name, _time
| where count > 0

Wazuh OSSEC Rule

<group name="linux,privilege_escalation,">
  <rule id="100001" level="12">
    <if_sid>550</if_sid>
    <field name="audit.exe">/usr/bin/sudo|/bin/su|/usr/bin/pkexec</field>
    <description>CVE-2026-79806: Possible privilege escalation via ClearPass OnGuard agent - suspicious root execution</description>
    <group>privilege_escalation,cve_2026_79806,</group>
  </rule>
  <rule id="100002" level="14">
    <if_sid>550</if_sid>
    <field name="audit.exe">/opt/onguard|/opt/ClearPass|/usr/local/onguard</field>
    <field name="audit.uid">0</field>
    <description>CVE-2026-79806: ClearPass OnGuard agent binary executed as root - potential exploitation attempt</description>
    <group>privilege_escalation,cve_2026_79806,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source).

1. Immediate mitigations:

   • Restrict local login access to Linux endpoints running the OnGuard agent to trusted administrators only.
   • Enforce least privilege: avoid granting interactive shell access to non-administrative users on affected hosts.
   • Monitor for suspicious process activity (e.g., shell spawning from the OnGuard agent) using the detection rules above.
   • If feasible, temporarily disable the OnGuard agent on non-critical systems, weighing the impact on NAC compliance.
   • Apply strict file system permissions and audit setuid/setgid binaries associated with the agent.

2. Patch/upgrade steps:

   • No vendor patch is currently available. Monitor Aruba/HPE security advisories and the NVD entry for updates.
   • Once a patch is released, test and deploy it promptly to all affected Linux endpoints.
   • Subscribe to vendor notification channels for ClearPass Policy Manager and OnGuard agent updates.

3. Long-term hardening:

   • Implement application allowlisting to prevent unauthorized binaries from executing with elevated privileges.
   • Use mandatory access control (SELinux/AppArmor) to confine the OnGuard agent and limit its ability to perform arbitrary privileged operations.
   • Regularly audit endpoint agents for privilege separation weaknesses.
   • Adopt a defense-in-depth strategy: assume local privilege escalation vulnerabilities will occur and limit the value of root access through network segmentation and credential hygiene.

References

1. NVD – CVE-2026-79806: https://nvd.nist.gov/vuln/detail/CVE-2026-79806
2. Aruba/HPE Security Advisories: https://www.arubanetworks.com/support-services/security-bulletins/
3. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog (CVE not listed as of reporting)
4. FIRST EPSS: https://www.first.org/epss/ (score not yet available)
5. MITRE ATT&CK – T1068 Exploitation for Privilege Escalation: https://attack.mitre.org/techniques/T1068/

No known threat actor campaigns or exploit-in-the-wild evidence are available for this CVE at this time.