CVE-2026-77097: Commvault Authentication Bypass Vulnerability

CVE-2026-77097 Overview

CVE-2026-77097 is a missing authentication vulnerability [CWE-306] in the Commvault Private Metrics Server. The flaw affects the metrics upload functionality and service availability of the component. Unauthenticated network attackers can abuse the exposed functionality without any user interaction. Commvault addressed the issue in a maintenance release and instructs customers to update the Private Metrics Server. The vulnerability primarily impacts service availability and integrity of ingested metrics data.

Critical Impact
Remote, unauthenticated attackers can disrupt the Private Metrics Server and tamper with metrics upload functionality, degrading availability of a core Commvault telemetry service.

Affected Products

Commvault Private Metrics Server (see vendor advisory for affected versions)
Commvault backup and recovery deployments that expose the Private Metrics Server
On-premises Commvault installations reachable over the network

Discovery Timeline

2026-09-08 - CVE-2026-77097 published to NVD
2026-09-11 - Last updated in NVD database

Technical Details for CVE-2026-77097

Vulnerability Analysis

The Private Metrics Server ships with a missing authentication condition on the code path that handles metrics uploads. Requests reach the upload handler without being validated against an authenticated session or credential. Because the component is network-accessible, an attacker can interact with the endpoint directly. The advisory scopes the impact to metrics upload functionality and service availability, indicating both data integrity and availability consequences. The issue does not require user interaction or elevated privileges. Commvault documents the affected component and fixed release in security advisory CV_2026_08_1.

Root Cause

The root cause is a missing authentication check [CWE-306] on a sensitive endpoint. The Private Metrics Server accepts and processes upload requests without verifying the caller. This design gap allows any network client with reachability to invoke functionality that should be restricted to trusted Commvault components.

Attack Vector

The attack vector is network-based and does not require authentication or user interaction. An attacker with network reach to the Private Metrics Server can submit crafted requests to the metrics upload interface. Successful abuse can corrupt or pollute uploaded metrics and disrupt server availability. Environments that expose the Private Metrics Server beyond a segmented management network face the highest exposure. Refer to the Commvault Security Advisory CV_2026_08_1 for authoritative technical details.

Detection Methods for CVE-2026-77097

Indicators of Compromise

Unexpected spikes or anomalies in metrics uploaded to the Private Metrics Server from unknown source addresses.
Requests to the metrics upload endpoint originating from hosts outside the documented Commvault infrastructure.
Unexplained restarts, crashes, or degraded performance of the Private Metrics Server service.
Gaps or inconsistencies in expected telemetry that suggest tampering or denial of service.

Detection Strategies

Inspect web server and application logs on the Private Metrics Server for unauthenticated requests to upload endpoints.
Correlate network flow data to identify sources connecting to the Private Metrics Server that are not sanctioned Commvault clients.
Baseline normal metrics volume and content, then alert on statistical deviations that may indicate injected or malformed data.

Monitoring Recommendations

Enable verbose access logging on the Private Metrics Server and forward logs to a centralized analytics platform.
Monitor service health, restart counts, and resource utilization for the Private Metrics Server process.
Alert on any inbound connections to the Private Metrics Server from outside the designated management subnet.

How to Mitigate CVE-2026-77097

Immediate Actions Required

Upgrade the Private Metrics Server to the fixed maintenance release identified in Commvault Security Advisory CV_2026_08_1.
Restrict network reachability of the Private Metrics Server to trusted Commvault components only.
Audit recent metrics upload activity and service logs for signs of unauthorized interaction.

Patch Information

Commvault has released a resolved maintenance update for the Private Metrics Server. Customers must upgrade to the version referenced in advisory CV_2026_08_1. Review the Commvault Security Advisory CV_2026_08_1 for the specific fixed builds and upgrade guidance applicable to your deployment.

Workarounds

Place the Private Metrics Server behind a firewall or ACL that only permits traffic from authorized Commvault hosts.
Isolate the server on a dedicated management VLAN and block direct exposure to user or internet-facing segments.
If patching is delayed, temporarily disable external access to the metrics upload endpoint until the update is applied.

bash

# Example: restrict inbound access to the Private Metrics Server
# Replace <allowed_cidr> with the trusted Commvault management subnet
iptables -A INPUT -p tcp --dport <metrics_port> -s <allowed_cidr> -j ACCEPT
iptables -A INPUT -p tcp --dport <metrics_port> -j DROP