CVE-2026-76738: HPE Networking Instant On Buffer Overflow

CVE-2026-76738 Overview

CVE-2026-76738 is a buffer overflow vulnerability in an API endpoint of HPE Networking Instant On. An authenticated attacker with administrative privileges can trigger the condition to cause a denial of service against the affected service. The service recovers automatically without manual intervention, limiting the operational impact.

The issue is classified under [CWE-119] (Improper Restriction of Operations within the Bounds of a Memory Buffer). HPE published a security bulletin describing the flaw and affected components. See the HPE Security Bulletin for vendor guidance.

Critical Impact
Authenticated administrators can interrupt the normal operation of the HPE Networking Instant On API service through a buffer overflow, producing a transient denial of service.

Affected Products

HPE Networking Instant On (see vendor advisory for affected versions)

Discovery Timeline

2026-09-29 - CVE-2026-76738 published to NVD
2026-09-30 - Last updated in NVD database

Technical Details for CVE-2026-76738

Vulnerability Analysis

The vulnerability resides in an API endpoint exposed by HPE Networking Instant On. When the endpoint processes crafted input, a buffer overflow condition is triggered within the request-handling logic. The overflow disrupts the affected service, resulting in a denial of service.

Exploitation requires administrative privileges, which limits the population of viable attackers. The service restarts automatically, so persistence of impact is bounded to the recovery window. Confidentiality and integrity are not affected based on the vendor-reported impact.

Root Cause

The root cause is improper restriction of operations within the bounds of a memory buffer [CWE-119]. Input handled by the API endpoint is not adequately validated for size before being written into a fixed-length buffer. This allows the underlying process to be forced into a fault state.

Attack Vector

The attack vector is network-based. An authenticated administrator sends a crafted request to the vulnerable API endpoint over the network. No user interaction is required to trigger the flaw once authenticated access is available.

Because exploitation requires high privileges, the risk profile is dominated by insider misuse or compromise of an administrative account. HPE has not reported public exploitation, and no proof-of-concept has been published. Refer to the HPE Security Bulletin for further technical detail.

Detection Methods for CVE-2026-76738

Indicators of Compromise

Unexpected restarts or crash logs from the HPE Networking Instant On API service.
Malformed or oversized requests directed at management API endpoints originating from administrative sessions.
Gaps in device telemetry or management-plane availability windows.

Detection Strategies

Correlate administrative API request patterns with service restart events to identify potential exploitation attempts.
Alert on repeated API errors or process termination events tied to the Instant On management service.
Baseline normal administrator API usage and flag deviations in payload size or request frequency.

Monitoring Recommendations

Ingest management-plane logs into a centralized SIEM for correlation across network device fleets.
Monitor administrative account activity for anomalous session sources, times, or command patterns.
Track service health metrics for the Instant On API and alert on unexpected recovery cycles.

How to Mitigate CVE-2026-76738

Immediate Actions Required

Apply the patched firmware identified in the HPE Security Bulletin.
Restrict administrative access to trusted management networks and enforce multi-factor authentication on administrator accounts.
Audit administrative account inventory and revoke unused or over-privileged credentials.

Patch Information

HPE has issued guidance and fixed versions through the vendor security bulletin. Consult the HPE Security Bulletin for the specific fixed firmware versions and upgrade instructions.

Workarounds

Limit exposure of the management API to dedicated management VLANs or jump hosts.
Enforce network access control lists that restrict which sources can reach administrative endpoints.
Continuously review administrative role assignments and remove standing privileges where feasible.

bash

# Example: restrict management API access at the network layer
# Replace 10.10.0.0/24 with your authorized management subnet
iptables -A INPUT -p tcp --dport 443 -s 10.10.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP