CVE-2026-73749

Executive Summary

CVE-2026-73749 describes multiple vulnerabilities in a daemon component of HPE Aruba AOS-CX network operating system that allows improper processing of malformed input. An unauthenticated remote attacker can exploit these flaws by sending specially crafted packets to the affected service, potentially achieving remote code execution with elevated privileges.

Given the CVSS base score of 9.8 and the network-adjacent attack vector, this vulnerability poses a critical risk to organizations running AOS-CX switches in production environments. As of this report, no vendor patch is available, no public exploit code exists, and the CVE has not been added to CISA's Known Exploited Vulnerabilities catalog. However, the severity and unauthenticated nature warrant immediate defensive action.

Technical Analysis

The NVD description for CVE-2026-73749 is intentionally sparse but conveys a critical vulnerability class: multiple memory-corruption or logic-error flaws in a network-accessible daemon within AOS-CX. The description states that "multiple vulnerabilities exist in a daemon" — the plural "vulnerabilities" suggests this CVE aggregates several related flaws discovered in a single service, likely disclosed together.

Vulnerability Mechanism

The core issue is improper processing of malformed input. This class of vulnerability typically manifests as one of the following:

1. Buffer overflow — the daemon fails to validate the length of incoming packet fields (e.g., vendor-specific TLVs, option fields, or length-prefixed data structures), allowing an attacker to overwrite adjacent memory.
2. NULL pointer dereference — malformed input causes the daemon to dereference an uninitialized or NULL pointer, leading to a denial-of-service or potential code execution if the attacker can control the pointer value.
3. Integer overflow — arithmetic on length fields derived from attacker-controlled input wraps around, leading to undersized buffer allocation followed by overflow.
4. Use-after-free — malformed sequences of requests cause the daemon to access freed memory, which can be redirected to attacker-controlled data.

The phrase "remote code execution with elevated privileges" indicates that successful exploitation yields more than the privilege level of the daemon process itself. This suggests either the daemon runs as root (common for network device management processes) or the exploit chains additional privilege-escalation steps within the OS.

Attack Surface

AOS-CX is Aruba's network operating system for data-center and campus switches. The affected daemon is network-reachable, meaning it listens on one or more TCP/UDP ports for management or control-plane traffic. Typical daemons in AOS-CX include:

• REST API/Web UI management service (HTTPS, port 443)
• SNMP agent (UDP 161/162)
• SSH daemon (port 22)
• CLI management interface
• LLDP (Link Layer Discovery Protocol, Ethernet type 0x88CC) — often the culprit for malformed-input vulnerabilities

Given the CVSS vector (AV:N — network, not adjacent), the affected daemon is reachable over routable IP networks, not just link-local. The AC:L (attack complexity: low) suggests exploitation does not require special conditions such as race windows or heap grooming.

CWE Classification

While the official CWE is listed as N/A, the most appropriate mapping is CWE-20 (Improper Input Validation). Sub-classifications may include CWE-787 (Out-of-bounds Write), CWE-125 (Out-of-bounds Read), or CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). Without further detail, CWE-20 is the most defensible classification.

Exploitation Scenarios

Attack Chain Inference — No public PoC exists and no exploit code is available. The following attack chain is inferred from the vulnerability class (improper input validation leading to remote code execution) and the CVSS vector.

Step 1: Reconnaissance / Target Identification

An attacker would scan for AOS-CX devices using Shodan or masscan, looking for:

• Aruba management interfaces (HTTPS on 443, http.title:"Aruba")
• Open management ports (SSH :22, SNMP :161/162)
• Network topology mapping via LLDP/CDP responses

AOS-CX devices are commonly used in enterprise data centers and campus networks, making them high-value targets. The attacker would also identify the firmware version (often exposed via banner or web interface) to confirm vulnerability compatability.

Step 2: Triggering the Flaw

The attacker crafts specially formed packets targeting the vulnerable daemon's listening port. For a network management daemon, this might involve:

• Malformed HTTP requests with manipulated Content-Length headers or chunked encoding
• An SNMP SET/GET with malformed type-length-value (TLV) payloads
• A specially crafted LLDP frame (if the daemon handles LLDP on the control plane) with oversized TLV length fields
• A malformed OSPF/BGP packet if the daemon handles routing protocol processing

Because the attack complexity is low, the malformed input does not require precise timing or heap manipulation — a single carefully constructed packet may be sufficient to trigger the flaw.

Step 3: Payload / Execution Method

Once the malformed input corrupts memory, the attacker achieves code execution. For network daemons, common payload strategies include:

• Writing shellcode into the overflow buffer and redirecting the return address or function pointer to it
• Leveraging the daemon's running context (often root) to spawn a reverse shell via system() or execve()
• Installing a persistent backdoor in flash memory (e.g., modifying startup scripts, adding an SSH key to the admin account)

The description specifies "elevated privileges," meaning the daemon's own privilege level is already sufficient for full device control, or the exploit includes a privilege escalation stage.

Step 4: Post-Exploitation Impact

With elevated privileges on the switch, the attacker can:

• Capture all network traffic traversing the switch (span port mirroring)
• Modify ACLs, VLANs, and routing tables to redirect traffic (MITM position)
• Persist via config file modification or hidden management process
• Use the switch as a lateral movement pivot into the rest of the network
• Disable security controls (deny all firewall rules, disable logging)

In-the-wild evidence: None reported. No threat actor campaigns are currently associated with this CVE.

Impact Assessment

CVSS Analysis (9.8 / Critical):

Business Impact:

• Operational disruption: AOS-CX switches are critical network infrastructure. Compromise or reliability loss directly impacts application availability and user connectivity.
• Data breach risk: Traffic interception capability makes this a serious data-exposure risk for enterprises handling sensitive data.
• Network pivot risk: A compromised switch serves as an ideal staging point for lateral movement into server and workstation segments.
• Supply-chain implication: Aruba AOS-CX is widely deployed in enterprise, education, and government sectors, broadening the attack surface.

Affected systems: All AOS-CX products running the affected daemon — likely data-center switches (8325, 8360, 8400 series) and campus switches (6300, 6400 series), based on typical AOS-CX deployment, despite the exact version range not being disclosed.

Blast radius: If the switch is in a network spine or core position, the blast radius includes all connected segments. If in access position, the blast radius is limited to the connected endpoints.

Detection Guidance

Sigma Rule

title: AOS-CX Daemon Malformed Input Exploitation Attempt
id: 6f3a4c28-8b72-4e1a-9c0d-2f7de91a4b63
status: experimental
description: Detects network traffic patterns consistent with malformed input targeting AOS-CX management daemon
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-73749
author: Valtersit Threat Intelligence
date: 2026/02/15
logsource:
    category: network_connection
    product: firewall
detection:
    selection_tcp:
        destination.port:
            - 443
            - 22
            - 161
        protocol: tcp
        bytes_out: '> 65535'
    selection_anomaly:
        tcp.flags: '0x02'  # SYN packet with unusual payload
    condition: selection_tcp and not selection_anomaly
level: high
tags:
    - attack.initial_access
    - attack.t1190
    - cve.2026-73749

YARA Rule

rule CVE_2026_73749_AOSCX_Malformed_Input
{
    meta:
        author = "Valtersit Threat Intelligence"
        description = "Detects payload patterns associated with AOS-CX daemon malformed input exploitation"
        cve = "CVE-2026-73749"
        date = "2026-02-15"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-73749"
    strings:
        // Common overflow trigger patterns: long strings in protocol fields
        $a = "A" * 256
        $b = "\x90\x90\x90\x90\x90\x90" ascii  // NOP sled heuristic
        $c = "\x00\x10\xff\xff\x00\x01"       // potential integer overflow trigger
        $d = { FF FF FF FF 00 00 00 00 }      // large length field heuristic
        $e = "POST /rest/ v" ascii nocase      // REST API endpoint typical in AOS-CX
    condition:
        uint16(0) == 0x2E23 or                // LLDP EtherType
        any of them
}

Suricata IDS Rule

alert tcp any any -> $AOSCX_SWITCHES any (msg:"CVE-2026-73749 AOS-CX Daemon Malformed Input Attempt"; flow:to_server,established; content:"|00 00|"; depth:2; content:"|ff ff|"; within:10; classtype:attempted-admin; sid:10073749; rev:1; reference:cve,2026-73749; priority:1;)

Elastic Detection

sequence by source.ip with maxspan=30s
  [ network where destination.port == 443 and
    network.protocol == "http" and
    http.request.bytes > 100000 ]
  [ network where destination.port == 443 and
    network.protocol == "http" and
    http.response.status_code == 500 or
    http.response.status_code == 502 ]

Splunk SPL Query

index=firewall OR index=netflow
| where dest_port IN (443, 22, 161)
| eval packet_size = bytes_out
| where packet_size > 60000
| stats count min(_time) max(_time) by src_ip, dest_ip, dest_port
| where count > 3
| eval severity = "high"
| table _time, src_ip, dest_ip, dest_port, count, severity

Wazuh OSSEC Rule

<group name="cve-2026-73749,">
  <rule id="100284" level="15">
    <if_sid>5710</if_sid>
    <field name="srcip">!127.0.0.1</field>
    <regex>POST /rest/|SNMP|LLDP</regex>
    <description>CVE-2026-73749 - Potential AOS-CX daemon malformed input exploitation from srcip</description>
    <group>attack.initial_access,</group>
  </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED

As of this report, there is no vendor patch, no workaround published, and no version information to indicate which releases are affected or fixed. This is a critical gap that requires compensating controls.

1. Immediate Mitigations (compensating controls):

• Network segmentation: Restrict access to AOS-CX management plane to trusted, authorized IP ranges only. Use ACLs on the management VLAN or out-of-band management network.
• Disable unused services: If the vulnerable daemon is identifiable (e.g., SNMP, LLDP), disable it if business operations permit.
• Enable control-plane policing: Configure CoPP (Control Plane Policing) to rate-limit management protocols and drop anomalous traffic.
• Deploy IDS/IPS: Place network intrusion detection inline or monitor traffic to the management interfaces for the patterns indicated in the detection rules above.
• Traffic filtering: Use network-level filters to block malformed packet patterns that trigger the vulnerability (e.g., overly long SNMP/HTTP messages).

2. Patch/Upgrade Steps:

• Monitor Aruba Security Advisory RSS feed and the HPE Support Center for an official advisory for CVE-2026-73749.
• Subscribe to CISA KEV catalog updates — when this CVE is added (or if it is later added), prioritize patching.
• Until a patch is available, downgrade/avoid exposing AOS-CX management interfaces to untrusted networks (including the internet; if exposed, close those firewall rules immediately).

3. Long-Term Hardening:

• Enable ArubaOS-CX embedded security features: REST API authentication, SNMPv3 with encryption, and control-plane policing.
• Implement full network segmentation between management and data planes.
• Routinely audit management-plane logs for failed or malformed connection attempts.
• Establish a vendor-communication channel (Aruba support account) to receive early vulnerability notifications.
• Include AOS-CX devices in a vulnerability management program with regular scanning and version tracking.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2026-73749
2. Vendor Advisory (Aruba/HPE): Anticipated at https://www.arubanetworks.com/support-services/security-bulletins/ — check for CVE-2026-73749 advisory
3. MITRE ATT&CK T1190: https://attack.mitre.org/techniques/T1190/ — Exploit Public-Facing Application
4. CISA KEV Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog — CVE not currently listed
5. CWE-20 Reference: https://cwe.mitre.org/data/definitions/20.html — Improper Input Validation

Threat-actor activity: None reported in tracking sources at this time. No exploit code, no PoC, no in-the-wild evidence. This is a pre-disclosure or early-disclosure stage threat.