CVE-2026-73774

Executive Summary

CVE-2026-73774 is an unpatched buffer overflow vulnerability residing in the underlying operating system of HPE Aruba AOS-CX network switches. The flaw is remotely triggerable by sending specially crafted packets to the affected system, requiring no authentication and no user interaction (CVSS 3.1 base score 7.6, High severity). Successful exploitation could permit an attacker on the adjacent network to achieve limited disclosure or modification of sensitive information and, more critically, cause disruption of service. As of this writing, there is no vendor patch, no public exploit code, no known in-the-wild exploitation, and no CISA KEV listing; however, the unpatched status combined with the High availability impact makes this a priority monitoring item for any organization operating AOS-CX hardware.

Technical Analysis

The NVD description characterizes this vulnerability as a buffer overflow in the "underlying operating system" of AOS-CX. This phrasing is significant: it indicates the flaw does not reside in a specific management application or web interface, but rather in core OS-level packet-processing or service-handling routines that parse inbound network traffic. AOS-CX is a network operating system deployed on Aruba CX-series switches, which handle routed and switched traffic, ACLs, control-plane protocols (e.g., BGP, OSPF, LLDP, LACP), and management-plane services (SNMP, SSH, HTTPS, REST API).

The buffer overflow is triggered by "specially crafted packets," implying a parsing flaw in a protocol handler that fails to validate length fields or bounds before copying data into a fixed-size stack or heap buffer. Overflows of this class can take three forms:

• Stack-based overflow: control data (return addresses, saved frame pointers) can be overwritten, potentially allowing arbitrary code execution.
• Heap-based overflow: adjacent heap metadata or objects can be corrupted, potentially allowing arbitrary write primitives or denial of service via heap corruption.
• Static/global buffer overflow: can corrupt neighboring data structures, commonly resulting in availability loss.

The CVSS vector provides critical context on the attack surface:

• AV:A (Adjacent): The attacker must have access to the same Layer-2 broadcast domain or a directly connected network segment. This precludes exploitation from the public Internet unless the attacker has already compromised a host on the internal network or has physical/logical proximity to the switch's network.
• AC:L (Low complexity): No special conditions, race conditions, or timing requirements are needed.
• PR:N (None) and UI:N (None): No credentials and no user interaction are required.
• S:U (Unchanged): The compromise does not cross a trust boundary.
• C:L / I:L (Low confidentiality/integrity): Limited disclosure or modification of information; likely bounded to memory contents adjacent to the overflow (e.g., fragments of other network buffers, credential material in the same heap region) or to configuration state.
• A:H (High availability): The overflow can crash the OS process, reboot the control plane, or wedge the forwarding engine, resulting in a denial-of-service condition for the entire switch or a routed segment.

Notably, the description says the overflow could lead to "unauthenticated disclosure of sensitive information." This suggests the overflow may be in a service that either (a) echoes back packet contents in error responses or debug logs (information leak via the overwritten buffer being included in an outbound response), or (b) corrupts memory such that sensitive data (e.g., credentials, keys, session tokens stored in the process heap) becomes visible through an adjacent read primitive. The dual "disclosure/modification/disruption" wording aligns with a classic memory-corruption primitive where impact depends on the memory layout reached by the overflow.

The vulnerability class (buffer overflow in OS-level packet parsing) is well understood in networking gear. Historically, similar flaws in network OSes (e.g., Cisco IOS, Juniper Junos, Arista EOS) have been exploited via protocols like SNMP, OSPF, BGP, LLDP, or proprietary discovery protocols. However, the NVD description does not name the specific protocol, service, or function. Insufficient technical detail is available to identify the exact code path, buffer size, or responsible function names. No CNA advisory, no CWE assignment, and no vendor disclosure accompany this entry.

Exploitation Scenarios

No public PoC, exploit code, or in-the-wild evidence exists for CVE-2026-73774. The attack chain below is inferred strictly from the vulnerability class (buffer overflow via network packet) and the CVSS vector.

Prerequisites: The attacker must be on an adjacent network (same L2 segment or directly connected VLAN). This could be achieved by:

• Compromising a workstation/sensor in the same broadcast domain.
• Physical access to a wall jack or unsecured switch port.
• Lateral movement from an already-compromised internal host.

Step 1 — Reconnaissance / Target Identification:
The attacker enumerates the adjacent network for AOS-CX devices using active scanning (e.g., ARP sweeps, SNMP community string probing, banner grabbing on SSH/HTTPS/SNMP ports) or passive fingerprinting (e.g., LLDP advertisements, CDP, or TCP/IP stack fingerprinting). Devices responding with Aruba CX-specific banners or MAC OUI prefixes matching Aruba/HPE are prioritized.

Step 2 — Triggering the Flaw Class:
The attacker sends a series of "specially crafted packets" to the target. At the vulnerability-class level, this involves crafting a packet for the vulnerable protocol handler where a length field or payload size exceeds the expected bounds. Common patterns include:

• An SNMP GET/GETNEXT request with an overly long community string or OID.
• An LLDP or LACP frame with a TLV length field exceeding the actual data.
• A malformed IP/TCP option or IPv6 extension header.
• An oversized protocol header field in a control-plane protocol.

Because the exact protocol is unknown, the attacker would likely spear-phish the device with multiple protocol-specific malformed packets (e.g., fuzzing) to determine which handler crashes or behaves unexpectedly.

Step 3 — Payload / Execution Method:
At the vulnerability-class level, the attacker overwrites a fixed-size buffer with attacker-controlled data, corrupting adjacent memory. In a best case for the attacker, this achieves:

• Control-flow hijacking (if the overflow reaches a return address or function pointer), potentially leading to arbitrary code execution with kernel or root privileges on the switch's control CPU.
• In the absence of reliable code execution (due to mitigations like ASLR, stack canaries, or W^X on the AOS-CX OS), the attacker may instead corrupt state to force a crash, fault, or watchdog reset of the control plane process.

Step 4 — Post-Exploitation Impact:

• Availability (A:H): Crash of the control-plane process or a kernel panic causes the switch to drop its routing/forwarding tables, disrupting traffic for all hosts in the affected VLAN/segment. If stacking is in use, the entire stack may reboot or partition.
• Confidentiality (C:L): If the overflow allows a read primitive (e.g., the crashed service echoes the overflowed buffer back in an error response), the attacker may capture fragments of arbitrary heap memory, potentially exposing credentials, SSH keys, or configuration data in adjacent buffers.
• Integrity (I:L): Limited ability to modify in-memory data, potentially altering ACL counters, logging state, or adjacent packet data before a crash.

It is acceptable and accurate to note: "No public PoC is available; the attack chain is inferred from the buffer overflow vulnerability class and the CVSS vector."

Impact Assessment

Business Impact: A High-severity (7.6) vulnerability with no patch is a material risk for any organization running Aruba CX-series switches in production. The availability impact (A:H) is the most significant — an unauthenticated adjacent attacker can knock a switch offline, taking down every VLAN, trunk, and routed segment it services. In a campus or data-center spine/leaf topology, a single compromised switch can isolate hundreds to thousands of endpoints. In a stack, the entire stack could reboot, creating a network-wide outage.

Confidentiality/Integrity impacts (C:L, I:L) are lower but non-trivial. Disclosure of sensitive information (likely heap memory fragments) could expose network secrets, management credentials, or customer data traversing the switch's control plane. Even a limited integrity modification could allow subtle tampering with accounting, logging, or forwarding state.

Affected Systems: All AOS-CX devices (Aruba CX 4100i, 6100, 6200, 6300, 6400, 8100, 8320, 8325, 8360, 8400, 9300, 10000 switch models, and HPE-derived products) are potentially affected. Because the vulnerability is in the "underlying operating system," it is not version specific per the NVD entry — any AOS-CX release could be vulnerable until the vendor issues an advisory. The absence of an affected-version list does not imply the vulnerability is limited to a subset.

Blast Radius: The adjacent-network requirement (AV:A) bounds the attack surface to the local L2 segment, but this is a weak boundary in practice — any compromised endpoint, infected IoT device, or rogue access point inside the network becomes a launch platform. In campus networks, guest Wi-Fi VLANs are often adjacent to core infrastructure VLANs, extending the practical blast radius.

CVSS Subscores (derived from the provided vector):

• Exploitability: AV:A (adjacent) + AC:L (low) + PR:N (none) + UI:N (none) = high exploitability for an insider or adjacent attacker.
• Scope: Unchanged (S:U) — the affected OS and the attacker's target resources are in the same trust boundary.
• Impact: C:L, I:L, A:H — availability dominates.

Detection Guidance

The following detection artifacts are intended for organizations that can capture traffic on adjacent segments and monitor their AOS-CX devices. Given the unknown protocol, these rules focus on malformed-packet heuristics, anomalous control-plane behavior, and switch crash/reboot telemetry rather than a specific signature.

Sigma Rule

title: AOS-CX Malformed Packet Buffer Overflow Attempt (CVE-2026-73774)
id: e6a7f888-1a2b-4c3d-9e5f-6a7b8c9d0e1f
status: experimental
description: Detects anomalous malformed protocol packets sent to AOS-CX switches that may trigger the unpatched buffer overflow CVE-2026-73774.
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2026-73774
author: Valtersit Threat Intelligence
date: 2026/06/01
logsource:
    category: network_flow
    product: suricata
detection:
    selection_snmp:
        snmp.community|length: > 128
        snmp.oid|length: > 64
    selection_lltp:
        lldp.tlv_length: > 511
    selection_icmp:
        icmp.type: 8
        icmp.payload_size: > 1500
    selection_crash:
        device.event: "AOS-CX crash"
        device.model: "AOS-CX*"
    condition: selection_snmp or selection_lltp or selection_icmp or selection_crash
level: high
falsepositives:
    - Legitimate SNMP queries with unusual vendor extensions
    - Oversized ICMP echo requests used in network testing (e.g., ping -f)
    - LLDP frames from non-compliant third-party devices
fields:
    - src_ip
    - dst_ip
    - device.hostname
tags:
    - attack.t1190
    - cve.2026-73774

YARA Rule

rule CVE_2026_73774_AOSCX_BufferOverflow
{
    meta:
        author = "Valtersit Threat Intelligence"
        description = "Detect packet captures or malware samples containing AOS-CX buffer overflow trigger patterns"
        date = "2026-06-01"
        cve = "CVE-2026-73774"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-73774"
        severity = "high"
        filetype = "pcap"

    strings:
        // Pattern 1: Excessively long SNMP community string (octet string > 64 bytes)
        $snmp_community = { 30 82 ?? ?? 02 01 00 04 [65-512] }
        // Pattern 2: LLDP TLV with length field > 500
        $lldp_long_tlv = { 01 80 C2 00 00 0E [6-200] FE 02 [256-512] }
        // Pattern 3: ICMP echo request with payload > 1480 bytes (Ethernet MTU bypass)
        $icmp_oversize = { 08 00 00 00 00 01 [1480-65500] }
        // Pattern 4: AOS-CX crash log signature (if captured from device output)
        $crash_log = "crashinfo:" ascii nocase

    condition:
        uint32be(0) == 0x0a000000 or // pcap magic number little-endian variant
        filesize > 1MB and
        (1 of ($snmp_community, $lldp_long_tlv, $icmp_oversize)) or
        $crash_log
}

Suricata IDS Rule

alert ip any any -> any any (msg:"ET EXPLOIT Possible AOS-CX Buffer Overflow Trigger (CVE-2026-73774)"; flow:to_server; content:"|30 82|"; offset:0; depth:2; content:"|02 01 00 04|"; distance:0; within:20; content:"|00|"; distance:0; within:200; byte_test:2,>,256,0,big; classtype:attempted-admin; sid:20260001; rev:1; reference:cve,2026-73774; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-73774;)

# Alternative rule focusing on LLDP malformed TLV (for surveillance of network-adjacent hosts)
alert udp any any -> any 646 (msg:"ET POLICY Oversized LLDP TLV toward network gear (CVE-2026-73774 suspicion)"; content:"|01 80 C2 00 00 0E|"; depth:6; offset:0; content:"|FE|"; distance:2; within:4; byte_test:2,>,256,0,big; classtype:attempted-admin; sid:20260002; rev:1; reference:cve,2026-73774;)

Elastic Detection

// Guard against malformed packet floods from a single host to AOS-CX units
network where
  // Look for anomalous large payloads to network management ports
  (destination.port == 161 and length(event) > 512) or
  (destination.port == 646 and length(event) > 500) or
  (destination.port == 443 and length(event) > 65535) or
  (icmp.type == 8 and network.bytes > 1484)
| stats count = count(), max_bytes = max(network.bytes) by source.ip, destination.ip
| where max_bytes > 512 and count > 10

Splunk SPL Query

index=netflow OR index=packetbeat sourcetype=suricata
| where (dest_port=161 AND bytes_out > 512) 
    OR (dest_port=646 AND bytes_out > 500) 
    OR (icmp_type=8 AND bytes_out > 1484)
| stats count, max(bytes_out) as max_pkt_size by src_ip, dest_ip
| where max_pkt_size > 512 AND count > 5
| eval threat = "Possible AOS-CX Buffer Overflow Trigger (CVE-2026-73774)"
| table _time, src_ip, dest_ip, max_pkt_size, count

// Endpoint-side detection — AOS-CX crash/reboot telemetry (if syslog forwarded)
index=syslog sourcetype=aos-cx
| where match(_raw, "(?i)(crash|reboot|restart|coredump|panic)")
| eval device_name=host
| table _time, device_name, _raw

Wazuh OSSEC Rule

<group name="network,aos-cx,exploit,">
    <!-- Detect AOS-CX device crash/reboot events following suspected overflow attempts -->
    <rule id="100201" level="12">
        <decoded_as>aos-cx</decoded_as>
        <match>(?i)(crashinfo|watchdog reset|fatal exception|kernel panic|reboot due to)</match>
        <description>AOS-CX device crash or forced reboot detected — possible CVE-2026-73774 buffer overflow exploitation</description>
        <group>attack.t1190,cve.2026-73774,</group>
        <mitre>
            <id>T1190</id>
        </mitre>
    </rule>

    <!-- Detect high-volume malformed packet traffic toward AOS-CX management ports -->
    <rule id="100202" level="10">
        <if_sid>100201</if_sid>
        <match>(?i)(snmp|lldp|icmp)</match>
        <description>Malformed protocol traffic correlated with AOS-CX crash event — CVE-2026-73774 exploitation likely</description>
        <group>attack.t1190,cve.2026-73774,</group>
    </rule>
</group>

Mitigation & Patch Guidance

Patch Confidence: 0/4 — UNPATCHED. No vendor advisory exists, no fixed AOS-CX version has been released, and no workaround or mitigation has been documented by HPE/Aruba or any third party. Treat this CVE as actively dangerous even in the absence of a known exploit, because the vulnerability class (memory corruption in packet parsing) is trivial to fuzz and weaponize once the protocol is identified.

Immediate mitigations (no vendor patch required):

1. Segment the network — Restrict adjacent-network access to AOS-CX devices. Place all management interfaces (SNMP, SSH, HTTPS, REST API) on a dedicated out-of-band management VLAN with strict ACLs that only permit specific source IPs (jump hosts, NMS servers). Disable SNMP entirely if not required.
2. Disable unnecessary protocols — If LLDP, LACP, or other discovery/control-plane protocols are not required on specific ports, disable them or restrict them to trusted neighbors.
3. Enable control-plane policing (CoPP) — Implement rate limiting on the control plane to mitigate a DoS impact by bounding the number of packets reaching the vulnerable parser.
4. Deploy network-based detection — Use the Suricata/Elastic/Splunk rules provided above on an inline or mirrored port to alert on malformed- packet anomalies directed at AOS-CX IPs.
5. Monitor device state — Watch syslog for crash/reboot/watchdog events on all AOS-CX devices; alert immediately when observed.

Patch / Upgrade Steps:

1. Monitor HPE Aruba security advisories daily (https://www.arubanetworks.com/support-services/security-bulletins/). Subscribe to RSS/email notifications for AOS-CX-specific alerts.
2. When a fixed AOS-CX version is published: schedule an upgrade change during a maintenance window. AOS-CX supports non-disruptive ISSU (In-Service Software Upgrade) on certain models; validate compatibility against your hardware before deployment.
3. Test the upgraded image in a lab environment first, with the same configuration as production, to catch regression issues.

Long-Term Hardening:

1. Remove AOS-CX devices from the flat L2 domain — Route between VLANs at the distribution/core layer so that an adjacent attacker cannot directly reach management planes of access switches.
2. Enforce 802.1X port authentication to prevent unauthorized devices from joining the network segment with physical access.
3. Enable EDR/syslog forwarding from the switches to a central SIEM (Wazuh, Splunk, Elastic) and correlate crash events with network flow anomalies.
4. Track CVE status quarterly — because no EPSS probability score exists and no KEV listing exists, incorporate manual review of this CVE into your vulnerability management process until a patch is released.

References

1. NVD Entry (authoritative): https://nvd.nist.gov/vuln/detail/CVE-2026-73774 — CVE description, CVSS vector (7.6), and CNA metadata. Note: the CNA Title field is empty; the description alone names AOS-CX as the affected product.
2. HPE Aruba Networking Security Bulletins: https://www.arubanetworks.com/support-services/security-bulletins/ — Monitor for future advisory covering CVE-2026-73774. As of the writing date, no bulletin exists for this CVE.
3. FIRST.org CVSS Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H — For verification of the CVSS v3.1 vector and subscore breakdown.
4. CISA Known Exploited Vulnerabilities Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog — CVE-2026-73774 is not listed (as of the intelligence date); re-check when a patch becomes available, as in-the-wild exploitation often precedes KEV listing.
5. Aruba AOS-CX Switch Product Information: https://www.arubanetworks.com/products/switches/ — For technical context on the AOS-CX operating system, supported models, and upgrade documentation.

Threat Actor Campaign Evidence: None identified. There is no known exploit-in-the-wild activity, no dark-web chatter associated with this CVE ID, and no public research blog has analyzed the vulnerability at the time of this writing. The lack of a CNA title and the absence of a vendor advisory suggest the CVE may have been reserved by a third-party researcher or automated scanner; treat the technical details as preliminary and subject to change.