CVE-2026-76736: HPE Networking Instant On Buffer Overflow

CVE-2026-76736 Overview

CVE-2026-76736 is a buffer overflow vulnerability in the underlying operating system of HPE Networking Instant On devices. A low-privilege authenticated local attacker can trigger the flaw to interrupt normal operation of the affected service. The issue is scoped to availability impact only, with no reported confidentiality or integrity consequences. HPE has published a security bulletin acknowledging the flaw and providing remediation guidance.

Critical Impact
A local authenticated attacker with low privileges can cause a denial-of-service condition against the affected HPE Networking Instant On service by exploiting an operating-system-level buffer overflow.

Affected Products

HPE Networking Instant On (underlying operating system)

Discovery Timeline

2026-09-29 - CVE-2026-76736 published to the National Vulnerability Database (NVD)
2026-09-29 - Last updated in NVD database

Technical Details for CVE-2026-76736

Vulnerability Analysis

The flaw is a buffer overflow [CWE-121-class weakness] in the operating system that underpins HPE Networking Instant On devices. Exploitation requires local access and valid low-privilege credentials on the target device. Successful exploitation disrupts the affected service, producing a denial-of-service condition without exposing data or altering system state.

Because the attack vector is local and user interaction is not required, the practical exposure is limited to operators, administrators, and any process capable of authenticating to the device shell or management interface. HPE's advisory scopes the impact strictly to availability of the affected service.

Root Cause

The root cause is improper bounds checking in an operating system component consumed by HPE Networking Instant On. Input supplied by an authenticated local user is written to a fixed-size buffer without adequate validation, allowing adjacent memory to be corrupted. The corruption is sufficient to crash or destabilize the service but is not documented as leading to code execution.

Attack Vector

An attacker must first obtain low-privilege authenticated local access to the device. The attacker then submits crafted input to the vulnerable OS-level interface, overflowing the target buffer. The affected service terminates or enters an unstable state, resulting in loss of availability until the service or device is restarted.

No public proof-of-concept, exploit, or CISA KEV listing is associated with this CVE at the time of publication. See the HPE Security Bulletin for vendor-specific technical detail.

Detection Methods for CVE-2026-76736

Indicators of Compromise

Unexpected termination or restart of HPE Networking Instant On services on affected devices.
Crash logs, core dumps, or watchdog-triggered reboots correlated with local user sessions.
Repeated authentication events from a low-privilege local account preceding a service outage.

Detection Strategies

Monitor device syslog for service crash signatures, segmentation faults, and unexpected process restarts.
Baseline normal command and CLI input patterns for low-privilege accounts and alert on anomalous input lengths or unusual argument payloads.
Correlate authentication telemetry with subsequent availability events on the same device within a short time window.

Monitoring Recommendations

Forward HPE Networking Instant On logs to a centralized logging or SIEM platform for retention and correlation.
Track uptime and service-health metrics per device and alert on unplanned service restarts.
Review the local account inventory on each device and flag accounts that should not exist or that log in outside expected windows.

How to Mitigate CVE-2026-76736

Immediate Actions Required

Apply the firmware or software update referenced in the HPE Security Bulletin as soon as it is available for your deployment.
Inventory all HPE Networking Instant On devices and confirm current firmware versions against the vendor advisory.
Audit local user accounts on affected devices and remove or disable accounts that are not strictly required.

Patch Information

HPE has issued security bulletin hpesbnw05150en_us for this vulnerability. Refer to the HPE Security Bulletin for the list of fixed versions and upgrade procedures specific to affected HPE Networking Instant On products.

Workarounds

Restrict local management access to trusted administrators only and enforce strong authentication for any account with device-level access.
Place management interfaces on an isolated administrative network segment to reduce the population of users who can reach the device locally.
Implement device health monitoring so that service disruption from exploitation attempts is detected and responded to quickly.

bash

# Example: restrict management access via ACL until patching is complete
# (Adapt syntax to your HPE Networking Instant On management interface)
permit ip <admin-mgmt-subnet> any
deny   ip any any log