CVE-2026-73776

Executive Summary

CVE-2026-73776 is a signature verification bypass vulnerability in the command line interface (CLI) of HPE ArubaOS-CX, a network operating system powering Aruba CX series switches. An authenticated attacker with administrative privileges can exploit this flaw to bypass cryptographic signature checks and achieve arbitrary code execution on the underlying operating system, provided specific pre-conditions outside the attacker's control are met. The vulnerability carries a CVSS score of 7.9 (High), reflecting high confidentiality and integrity impact with scope change; however, no public exploit code or in-the-wild exploitation activity has been observed to date.

The affected product line is ArubaOS-CX, deployed primarily in enterprise campus and data center switching environments. Given the high privilege requirement (administrative access via CLI), the primary threat scenario involves a compromised administrator account or an insider threat actor. Successful exploitation grants the attacker code execution at the operating system level, effectively taking full control of the network switch — a critical network infrastructure component.

Technical Analysis

The vulnerability is classified under CWE-347 (Improper Verification of Cryptographic Signature), indicating a flaw in how ArubaOS-CX CLI verifies the authenticity or integrity of digitally signed content. The NVD description specifies that the flaw exists in the command line interface and enables a signature verification bypass.

Vulnerability Mechanism: Based on the vulnerability class (CWE-347), the affected feature likely accepts cryptographically signed payloads, packages, images, or configuration bundles through CLI commands. The verification process either fails to properly validate the signature, accepts an invalid signature, or can be bypassed through a logic flaw in the verification state machine. The description notes that exploitation requires "certain pre-conditions outside of the attacker's control," suggesting that the verification bypass may depend on environmental factors such as:

• Specific system configuration states or feature combinations
• Prior installation of components that alter the trust chain
• Timing or ordering of CLI operations relative to system bootstrap

Attack Surface: The attack surface is the AOS-CX command line interface, accessible over SSH, serial console, or potentially via management interfaces. Only users with administrative privileges (typically the admin user or users with administrator RBAC role) can reach the affected CLI commands. This significantly narrows the attack surface but elevates the severity of the compromise, as the attacker is already operating with high privileges.

Code-Level Context: Insufficient technical detail is available to identify specific affected commands, functions, or file paths. The NVD description lacks implementation-level specifics — no command names, function names, or parameters are disclosed. What is clear is that the signature verification logic governing CLI operations is deficient and can be circumvented, likely by supplying a specifically crafted but improperly signed input that the verification routine erroneously accepts.

Key Technical Characteristics:

• Privilege Required: High (administrative CLI access)
• User Interaction: None required
• Scope: Changed (compromise extends beyond the CLI process to the host OS)
• Impact: Code execution on the underlying operating system kernel
• Pre-condition dependency: Additional unspecified conditions must align

The existence of a signature verification mechanism implies the platform employs cryptographic controls to ensure only trusted content (e.g., software images, firmware updates, or signed configuration objects) is processed. The bypass undermines this trust boundary.

Exploitation Scenarios

No public PoC, exploit code, or Nuclei template is available. The attack chain below is inferred from the vulnerability class (signature verification bypass leading to code execution) and the constrained information in the NVD description.

Step 1 — Reconnaissance and Target Identification: The attacker must first obtain valid administrative credentials for an AOS-CX switch. This typically involves:

• Compromising an existing administrator account (e.g., via spear-phishing, credential theft, or password reuse)
• Insider threat — a legitimate administrator acting maliciously
• Lateral movement within the network to compromise management credentials

Once credentials are obtained, the attacker gains access to the CLI via SSH (port 22), the serial console, or out-of-band management interfaces.

Step 2 — Triggering the Signature Verification Bypass: The attacker interacts with the CLI using administrative commands that invoke the signature verification mechanism. While the specific command is undisclosed, the attacker would issue CLI commands designed to load, install, or process cryptographically signed content (e.g., software images, hotfix bundles, or signed configuration data). The attacker crafts a malicious payload designed to exploit the verification bypass — for example, a file with a malformed, missing, or self-signed signature that the flawed verification routine erroneously validates.

The "pre-conditions outside of the attacker's control" clause suggests the attacker may need specific system states (e.g., particular software build, enabled feature modules, or storage conditions) for the bypass to succeed. This introduces an element of uncertainty the attacker must manage, potentially requiring reconnaissance into the target switch's configuration and version.

Step 3 — Payload Execution: Once the falsely "verified" payload is accepted by the CLI, the attacker triggers the operation that processes the content (e.g., image installation, bundle apply, or configuration restore). The signature bypass allows attacker-supplied code to be trusted by the operating system, leading to arbitrary code execution on the underlying OS with elevated privileges, likely at the kernel or root level given the administrative context.

Step 4 — Post-Exploitation Impact: Successful execution grants the attacker complete control of the switch's underlying operating system. From this position, the attacker can:

• Install persistent backdoors or rootkits that survive reboots and software upgrades
• Intercept or redirect network traffic (given the switch's physical network position)
• Modify routing, ACLs, VLAN, or spanning-tree configurations to disrupt or eavesdrop on network traffic
• Leverage the switch as a pivot point for deeper network penetration
• Exfiltrate data traversing the switch
• Destroy the switch configuration (high availability impact)

The scope change metric (S:C) confirms that the compromise crosses the boundary from the CLI application into the host OS environment, enabling broad impact on the switch and the network segment it serves.

Impact Assessment

CVSS Breakdown: The CVSS vector CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N yields a base score of 7.9 (High):

• Attack Vector (Local): Exploitation requires local access to the device CLI — no remote exploitation path exists without first establishing administrative access.
• Attack Complexity (Low): No complex conditions beyond the stated "pre-conditions" that are outside attacker control; the bypass mechanism itself is not complex.
• Privileges Required (High): Administrative privilege on the CLI is mandatory — the single most significant mitigant.
• User Interaction (None): No user action required beyond the attacker's own operations.
• Scope (Changed): The compromise extends beyond the CLI software boundary into the switch's underlying operating system — a security domain escalation.
• Confidentiality (High): Full OS access allows reading of all local data, including configuration secrets, credentials, and potentially captured network data.
• Integrity (High): The attacker can modify any OS-level file, firmware component, or configuration.
• Availability (None): The CVSS scoring does not reflect direct availability impact, though code execution capability implicitly enables availability attacks.

Business Impact: Aruba CX switches are deployed as top-of-rack (ToR), spine, and campus core switching infrastructure. A compromised switch can serve as:

1. Network TAP/Eavesdropping Point: With OS-level access, an attacker can mirror or capture network traffic traversing the switch, compromising the confidentiality of all network communications.
2. Network Disruption Vector: An attacker can deliberately corrupt the switching fabric, forwarding tables, or management plane, causing widespread network outages.
3. Lateral Movement Platform: The compromised switch becomes a trusted pivot for further network penetration, allowing the attacker to reach adjacent devices and network segments.
4. Persistence Anchor: Backdoored network infrastructure generally goes undetected for extended periods and is difficult to remediate without complete device replacement or factory reset plus reimage.

Blast Radius: Exploitation of a single switch can compromise an entire network segment, data center row, or campus distribution layer. In environments without proper network segmentation and management plane protection, the impact could propagate to other switches and connected systems. The EPSS score of 0.00131 (3.0% percentile) indicates low current exploit likelihood, but this metric is dynamic and subject to change if exploit details emerge.

Who Is Affected: Enterprises running ArubaOS-CX on CX 4100i, 6000, 6100, 6200F, 6300F, 6400, 8100, 8320, 8325, 8360, 8400, 9300, and 10000 switch series are potentially affected, subject to specific version confirmation from HPE.

Detection Guidance

Detection of this vulnerability is challenging because exploitation occurs through legitimate administrative CLI sessions and involves the signature verification process, which is not typically instrumented with observable failure states. The following detections are baseline guidance and should be tuned to the organization's environment.

Sigma Rule

title: ArubaOS-CX Signature Verification Bypass - Anomalous CLI Admin Activity
id: 51d87e4a-2f1e-4b5a-9c3d-6a7f8b0c1d2e
status: experimental
description: Detects potentially anomalous administrative CLI activity on ArubaOS-CX switches that could indicate exploitation of CVE-2026-73776 (signature verification bypass).
references:
    - https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-73776
author: Valters IT Security Research
date: 2026/01/15
logsource:
    product: aruba
    service: aos-cx-cli
detection:
    selection_install:
        keywords:
            - 'copy * flash:'
            - 'software install'
            - 'boot system'
            - 'image *'
    selection_admin:
        keywords:
            - 'admin'
    selection_multiple_failures:
        # Multiple failed file checksum/signature operations may indicate probing
        keywords:
            - 'checksum'
            - 'signature'
            - 'verification failed'
        count: 3
    filter_baseline:
        keywords:
            - 'normal operation'
    condition: (selection_install and selection_admin) or selection_multiple_failures
level: high
falsepositives:
    - Legitimate software upgrade operations by authorized administrators
    - Normal configuration backup/restore procedures
tags:
    - attack.privilege_escalation
    - attack.t1203
    - cve.2026-73776

YARA Rule

/*
    YARA rule to detect potential malicious payloads targeting
    AOS-CX signature verification bypass (CVE-2026-73776)
    Detects suspicious files with forged or malformed signature structures
    commonly seen in image/package files processed by ArubaOS-CX CLI
*/
rule ArubaOS_CX_Signature_Bypass_CVE_2026_73776
{
    meta:
        author = "Valters IT Security Research"
        date = "2026-01-15"
        description = "Detects potential malformed/forged signature files targeting AOS-CX CLI signature bypass"
        reference = "CVE-2026-73776"
        cve = "CVE-2026-73776"
        score = 70

    strings:
        // AOS-CX image/package file headers
        $hdr_swi = "ARUBASWI" ascii wide
        $hdr_os = "AOS-CX" ascii wide
        $hdr_pkg = ".pkg" ascii wide

        // PKCS#7 / CMS signature structures that may be malformed
        $sig_cms = { 30 82 ?? ?? 06 09 2A 86 48 86 F7 0D 01 07 02 }
        $sig_rsa = "RSA-OAEP" ascii
        $sig_sha = { 30 31 30 0D 06 09 60 86 48 01 65 03 04 02 01 05 00 04 20 }

        // Obfuscated code markers
        $code_elf = { 7F 45 4C 46 }  // ELF magic
        $code_shell = "#!/bin/sh" ascii

        // Anomalous length fields in CMS structures (potential truncation)
        $anom_len = { 30 00 00 }  // zero-length sequence

    condition:
        uint16(0) == 0x5A4D or  // MZ header
        (
            (
                $hdr_swi or $hdr_os or $hdr_pkg
            )
            and
            (
                ($sig_cms and not $sig_sha) or
                ($anom_len) or
                ($code_elf and $code_shell)
            )
        )
}

Suricata IDS Rule

# Suricata rule to detect network traffic that may precede or indicate
# exploitation of CVE-2026-73776 - ArubaOS-CX signature verification bypass.
# Note: Exploitation requires CLI access; this rule detects anomalous uploads
# to switch management interfaces (SSH/Telnet) that carry suspicious content.

alert tcp $HOME_NET any -> $AOS_CX_SWITCHES 22 (msg:"ET EXPLOIT ArubaOS-CX CLI Suspicious Image Upload Detected (CVE-2026-73776)"; flow:established,to_server; content:"|53 53 48 2D 32 2E 30 2D|"; depth:20; content:"SWI"; distance:1000; within:2000; content:!"|0a 0a 0a|"; distance:0; within:5000; threshold:type limit, track by_src, count 1, seconds 3600; classtype:attempted-admin; sid:202673776; rev:1; metadata:created_at 2026_01_15, updated_at 2026_01_15, cve CVE-2026-73776, attack_target network_equipment, deployment perimeter, signature_severity Major, tag cve-2026-73776;)

alert tcp $HOME_NET any -> $AOS_CX_SWITCHES 22 (msg:"ET SUSPICIOUS ArubaOS-CX CLI Multiple Failed Signature Operations (CVE-2026-73776)"; flow:established,to_server; content:"|73 69 67 6E 61 74 75 72 65 20 76 65 72 69 66 69 63 61 74 69 6F 6E 20 66 61 69 6C 65 64|"; threshold:type both, track by_src, count 3, seconds 300; classtype:attempted-admin; sid:202673777; rev:1; metadata:created_at 2026_01_15, updated_at 2026_01_15, cve CVE-2026-73776, attack_target network_equipment, deployment perimeter, signature_severity Major, tag cve-2026-73776;)

alert tcp $HOME_NET any -> $AOS_CX_SWITCHES 22 (msg:"ET MALWARE ArubaOS-CX ELF Payload Uploaded over SSH (Potential CVE-2026-73776)"; flow:established,to_server; content:"|7F 45 4C 46|"; within:1000; classtype:attempted-admin; sid:202673778; rev:1; metadata:created_at 2026_01_15, updated_at 2026_01_15, cve CVE-2026-73776, attack_target network_equipment, deployment perimeter, signature_severity Major, tag cve-2026-73776;)

Elastic Detection

# Elastic EQL rule for detecting suspicious admin CLI activity on ArubaOS-CX
# that may indicate exploitation attempts of CVE-2026-73776.
# Correlate with switch auth logs (syslog), CLI session logs, and audit trails.

sequence by host.name with maxspan=5m
  [ any where event.module == "aruba" and event.dataset == "aoscx.cli"
     and process.name == "cli" and event.action in ("command-executed", "session-start") ]
  [ any where event.module == "aruba" and event.dataset == "aoscx.cli"
     and message in ("copy", "install", "boot", "checksum", "signature")
     and user.name in ("admin", "administrator") ]
  [ any where event.module == "aruba" and event.dataset == "aoscx.cli"
     and (message like "*verification failed*" or message like "*signature*invalid*")
     and event.action == "error" ]

For standalone Elastic EQL (no ECS context):

sequence with maxspan=10m
  [ any where process.name : "cli" and user.name : "admin"
     and message : ("*copy*", "*install*", "*image*") ]
  [ any where process.name : "cli" and user.name : "admin"
     and (message : "*failed*" or message : "*error*") ]
  [ any where process.name : "*shell*" or process.name : "*bash*"
     and user.name : "admin" ]

Splunk SPL Query

# Detection of potentially malicious admin activity on ArubaOS-CX
# indicative of CVE-2026-73776 signature verification bypass attempts.
# Tune index and sourcetype naming to match environment.

index=network_switches sourcetype=aoscx:cli OR sourcetype=aoscx:audit
| where user IN ("admin", "administrator") OR role="administrator"
| search (
    ("copy * flash:" OR "software install" OR "boot system *" OR "image *" OR "restore *") AND
    (
        "verification failed" OR
        "signature invalid" OR
        "checksum error" OR
        "unauthorized image" OR
        "permission denied"
    )
)
| eval threat_score = case(
    match(command, "(?i)(boot system|software install)"), 80,
    match(command, "(?i)(copy.*flash)"), 70,
    match(command, "(?i)(checksum|signature)"), 60,
    true, 40
)
| where threat_score > 50
| stats count as attempt_count earliest(_time) as first_attempt latest(_time) as last_attempt
      values(command) as attempted_commands values(src_ip) as source_ips by host
| where attempt_count >= 2
| eval severity = case(
    attempt_count > 5, "critical",
    attempt_count > 2, "high",
    true, "medium"
)
| table _time host src_ip user attempted_commands attempt_count severity first_attempt last_attempt
| sort - attempt_count

Wazuh OSSEC Rule

<group name="aruba,">
  <rule id="845478" level="12">
    <if_sid>2002000</if_sid>
    <field name="user">^(admin|administrator)$</field>
    <field name="command">\.(copy|install|boot|restore|upgrade)</field>
    <description>ArubaOS-CX: Administrative command invoking image/package processing - possible CVE-2026-73776 exploitation vector</description>
    <group>cve-2026-73776,</group>
    <mitre>
      <id>T1203</id>
    </mitre>
  </rule>

  <rule id="845479" level="15">
    <if_sid>2003776</if_sid>
    <match>verification failed|signature invalid|checksum error|unauthorized|not verified</match>
    <description>ArubaOS-CX: Signature verification failure followed by administrative content operation - potential CVE-2026-73776 exploitation attempt</description>
    <group>cve-2026-73776,</group>
    <mitre>
      <id>T1203</id>
    </mitre>
  </rule>

  <rule id="845480" level="15">
    <if_sid>2003777</if_sid>
    <regex>success|accepted|completed|installed|ok</regex>
    <description>ArubaOS-CX: Signature verification failed but content operation succeeded - HIGH CONFIDENCE CVE-2026-73776 exploitation</description>
    <group>cve-2026-73776,</group>
    <mitre>
      <id>T1203</id>
    </mitre>
  </rule>

  <rule id="845481" level="10">
    <if_sid>2003776</if_sid>
    <regex>session opened|login success</regex>
    <description>ArubaOS-CX: Administrative CLI session opened prior to content operation</description>
    <group>cve-2026-73776,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 2/4 (CLAIMED — single source claims patch, not independently confirmed). The NVD entry indicates a patch exists, but vendor advisory details and specific patched versions have not been independently verified. Organizations should verify patch availability directly through the HPE Aruba Security Advisory portal.

Immediate Mitigations (implement now):

1. Restrict administrative CLI access: Limit the number of personnel with administrative access to AOS-CX devices. Enforce least-privilege principles — delegate non-administrative tasks to users with read-only or operator roles.
2. Enforce strong authentication: Mandate multi-factor authentication (MFA) for all administrative CLI sessions. Use TACACS+ or RADIUS with MFA rather than local accounts on the switch.
3. Network-level access control: Restrict SSH and management plane access to trusted management VLANs/subnets only. Use management access lists (MAL) to limit CLI access to dedicated jump hosts or management stations.
4. Audit and monitor admin sessions: Ensure all administrative CLI sessions are logged to a central syslog server that is inaccessible from the switch itself (to prevent log tampering).
5. Segment management plane: Ensure management traffic is on a dedicated OOB (out-of-band) network that does not traverse the production data plane.

Patch and Upgrade Steps:

1. Monitor the HPE Aruba Security Advisory page regularly (https://www.arubanetworks.com/support-services/security-bulletins/) for official advisory and patch availability.
2. Contact HPE support or your Aruba account representative to confirm patch availability for your specific hardware model and software release train.
3. Follow HPE's standard patch management process:
   • Download the patched software image from the HPE support portal
   • Verify image checksum/signature per standard procedures
   • Schedule a maintenance window and upgrade the switch software
   • Verify post-upgrade functionality and confirm the running version
4. If no official patch is yet available, consider downgrading to a prior maintained release if a fix was silently backported, or escalate to HPE for interim remediation guidance.

Long-term Hardening:

1. Configuration management: Implement automated configuration backup and version control for all AOS-CX devices. Maintain known-good baselines to detect unauthorized changes.
2. Credential hygiene: Rotate administrative credentials periodically. Remove all default credentials. Disable local accounts in favor of TACACS+/RADIUS centralized authentication.
3. Continuous monitoring: Deploy the detection rules above and integrate switch audit logs with the organization's SIEM/SOAR platforms.
4. Network architecture reviews: Periodically review management plane architecture to minimize the exposure of administrative interfaces and align with zero-trust principles.
5. Vendor communication: Subscribe to the Aruba security notification service to receive early advisories for future vulnerabilities.
6. Regular vulnerability scanning: Include network infrastructure in vulnerability management program, checking for running software versions against vendor advisories.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-73776 — Official NVD record containing the description, CVSS vector (CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N, score 7.9), and CWE-347 classification.
2. HPE Aruba Security Advisories Portal: https://www.arubanetworks.com/support-services/security-bulletins/ — Official HPE/Aruba security bulletin repository. Check for advisory referencing CVE-2026-73776 for patch details and affected version information.
3. MITRE CWE-347: https://cwe.mitre.org/data/definitions/347.html — Weakness description for "Improper Verification of Cryptographic Signature," the vulnerability class underlying this CVE.
4. ArubaOS-CX Documentation (Aruba Networking): https://www.arubanetworks.com/techdocs/Aruba_OS_CX/html/ — Reference documentation for CLI commands and administrative procedures; consult for understanding command surface used in remediation.
5. FIRST CVSS Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N — CVSS vector verification for CVE-2026-73776.

Threat Actor / Exploit-in-the-Wild Status: No evidence of threat actor campaigns or exploitations in the wild. The CVE is NOT listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS score is 0.00131 (3.0% percentile of exploited CVEs), indicating very low probability of current exploitation. No public exploit code, PoC, or Nuclei template exists.