CVE-2026-77105 Overview
CVE-2026-77105 is a cryptographic signature verification vulnerability in Commvault CommServe that impacts privilege management. The flaw is categorized under [CWE-347] (Improper Verification of Cryptographic Signature). An authenticated remote attacker with low privileges can leverage the defect to compromise confidentiality, integrity, and availability of the affected system. Commvault has published a security advisory instructing customers to upgrade to a resolved maintenance release for both CommServe and Web Server components. The vulnerability affects Commvault deployments on both Linux and Microsoft Windows platforms.
Critical Impact
An attacker with low-privileged network access can bypass cryptographic signature validation to escalate privileges within the Commvault CommServe environment.
Affected Products
- Commvault CommServe (see vendor advisory for affected maintenance releases)
- Commvault Web Server (see vendor advisory for affected maintenance releases)
- Deployments on Linux and Microsoft Windows operating systems
Discovery Timeline
- 2026-09-08 - CVE-2026-77105 published to NVD
- 2026-09-09 - Last updated in NVD database
Technical Details for CVE-2026-77105
Vulnerability Analysis
The vulnerability resides in the CommServe component of the Commvault data protection platform. CommServe orchestrates backup, restore, and administrative operations and enforces role-based privilege boundaries across the environment. Because CommServe relies on cryptographic signatures to validate the authenticity of privileged operations, any weakness in that verification path directly undermines privilege management.
An attacker authenticated to the CommServe network interface can submit crafted requests that the signature validation logic fails to reject. This bypass permits actions that should be limited to higher-privileged roles. The result is unauthorized privilege escalation across the CommServe and Web Server surfaces exposed to the network.
Root Cause
The defect is an improper verification of a cryptographic signature, tracked as [CWE-347]. Signature verification is either incomplete, incorrectly implemented, or fails to enforce the cryptographic properties required to bind an operation to a trusted signer. When verification does not reject invalid or forged signatures, privilege boundaries enforced by that check collapse.
Attack Vector
Exploitation requires network access to CommServe and a low-privileged authenticated session. No user interaction is required. Commvault has not disclosed public proof-of-concept code, and no in-the-wild exploitation has been reported. Commvault's advisory (CV_2026_08_7) documents the affected releases and remediation. No verified exploit code is available; refer to the vendor advisory for technical details.
Detection Methods for CVE-2026-77105
Indicators of Compromise
- Unexpected privilege changes, role assignments, or administrative operations originating from low-privileged CommServe accounts.
- Web Server or CommServe audit entries showing signed operations that succeed despite anomalous signer or session metadata.
- New or modified scheduled tasks, credentials, or backup targets created outside normal change windows.
Detection Strategies
- Enable and forward CommServe and Web Server audit logs to a centralized SIEM for correlation against user role baselines.
- Alert on API and console operations that require elevated privileges when initiated by accounts that do not routinely perform them.
- Correlate authentication events with subsequent administrative actions to identify session-to-privilege mismatches.
Monitoring Recommendations
- Monitor network traffic to CommServe and Web Server endpoints from unexpected sources or over unusual ports.
- Track configuration changes to storage policies, client groups, and user security associations for unauthorized modifications.
- Review authentication logs for anomalous low-privilege accounts issuing signed administrative requests.
How to Mitigate CVE-2026-77105
Immediate Actions Required
- Apply the resolved Commvault maintenance release to both CommServe and Web Server components as directed in advisory CV_2026_08_7.
- Restrict network access to CommServe and Web Server management interfaces to trusted administrative networks only.
- Audit existing CommServe user accounts and revoke unnecessary privileges or unused low-privileged accounts.
Patch Information
Commvault has released fixed maintenance updates for CommServe and Web Server. Customers should consult the Commvault Security Advisory CV_2026_08_7 to identify the specific maintenance release corresponding to their deployed version and apply it to all CommServe and Web Server hosts.
Workarounds
- No official workaround is published by Commvault; upgrading to the fixed maintenance release is the supported remediation.
- As a compensating control, place CommServe and Web Server behind network segmentation and require VPN or bastion access for administration.
- Enforce multi-factor authentication on all Commvault administrative accounts to raise the barrier to authenticated exploitation.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
