CVE-2026-73783: AOS-CX API Stack Overflow DOS Vulnerability

CVE-2026-73783 Overview

CVE-2026-73783 is a stack overflow vulnerability in an API endpoint of HPE Aruba Networking AOS-CX. An authenticated attacker with high privileges can send crafted requests to the affected API endpoint to trigger the overflow. Successful exploitation causes a denial-of-service (DoS) condition on the switch, disrupting network availability. The flaw is categorized under [CWE-121: Stack-based Buffer Overflow]. It affects confidentiality and integrity minimally, but availability impact is high. HPE published a security bulletin addressing the issue.

Critical Impact
Authenticated attackers can crash AOS-CX devices through the vulnerable API endpoint, interrupting switching and routing services on affected network infrastructure.

Affected Products

HPE Aruba Networking AOS-CX (see vendor advisory for specific versions)
AOS-CX API endpoint component
HPE Aruba switches running vulnerable AOS-CX firmware

Discovery Timeline

2026-09-01 - CVE-2026-73783 published to NVD
2026-09-02 - Last updated in NVD database

Technical Details for CVE-2026-73783

Vulnerability Analysis

The vulnerability resides in an API endpoint of AOS-CX, the network operating system used across HPE Aruba Networking switches. Improper bounds checking on input processed by the endpoint allows attacker-controlled data to write beyond the fixed-size stack buffer allocated by the request handler. When the overflow corrupts stack metadata such as return addresses or saved frame pointers, the affected process terminates abnormally.

Exploitation requires valid, high-privilege authentication to the management interface. The CVSS vector indicates network-adjacent reachability with no user interaction, and the impact is limited to availability. Confidentiality and integrity are unaffected, which is consistent with a crash-only condition rather than a code execution primitive.

EPSS data places the probability of observed exploitation attempts at a low tier as of the enrichment date. No public proof-of-concept and no known in-the-wild exploitation are reported.

Root Cause

The root cause is a stack-based buffer overflow ([CWE-121]) in the request-handling path of an AOS-CX API endpoint. The handler copies input into a fixed-size stack buffer without validating input length against buffer capacity, allowing adjacent stack memory to be overwritten.

Attack Vector

An authenticated administrator-level attacker sends a crafted API request to the vulnerable endpoint over the network. The oversized payload triggers the overflow, corrupts the stack frame of the handling process, and forces the service or device to terminate, producing a denial-of-service condition. See the HPE Security Bulletin for technical specifics.

// No verified public proof-of-concept is available.
// Refer to the HPE security bulletin for technical details.

Detection Methods for CVE-2026-73783

Indicators of Compromise

Unexpected reboots or process crashes on AOS-CX switches without corresponding change activity
Gaps in syslog output followed by cold-start SNMP traps from Aruba switches
Abnormally large or malformed requests directed at AOS-CX management API endpoints
Authenticated API sessions from unusual source addresses preceding a device restart

Detection Strategies

Monitor AOS-CX system logs for crash dumps, watchdog resets, or process restart events referencing the API service
Enable and review API access logs to identify high-privilege sessions issuing anomalous request payloads
Correlate authentication events for administrator accounts with device availability metrics to spot post-login crashes

Monitoring Recommendations

Alert on repeated cold-boot SNMP traps or LINK-DOWN cascades affecting switch uplinks
Track administrative API usage volume and payload size distributions to establish a baseline
Ingest AOS-CX telemetry into a centralized SIEM or data lake for cross-device correlation
Restrict management-plane reachability so that only monitoring platforms can query the API

How to Mitigate CVE-2026-73783

Immediate Actions Required

Apply the fixed AOS-CX firmware version listed in the HPE Security Bulletin as soon as change windows allow
Restrict management API access to a dedicated out-of-band management network or trusted jump hosts
Rotate and audit administrator credentials to reduce the population of accounts that could reach the vulnerable endpoint
Enable logging and alerting on unexpected switch reboots to detect exploitation attempts

Patch Information

HPE has published a security bulletin (hpesbnw05134en_us) describing affected AOS-CX versions and providing fixed firmware releases. Consult the HPE Security Bulletin for the current patched build numbers and upgrade guidance specific to your switch model and deployment.

Workarounds

Limit access to the AOS-CX REST API using role-based access control and management VRF isolation
Enforce access control lists on the management interface to permit only authorized administrative hosts
Reduce the number of accounts granted high-privilege roles on AOS-CX devices
Disable the REST API on switches where it is not required for operations

bash

# Restrict AOS-CX management access to a dedicated management VRF
# and apply an ACL permitting only trusted administrative hosts.
configure terminal
 vrf mgmt
 https-server vrf mgmt
 access-list ip MGMT_ACL
  10 permit tcp 10.10.0.0/24 any eq 443
  20 deny tcp any any eq 443
 interface mgmt
  ip access-group MGMT_ACL in
end
write memory