CVE-2025-57788: Commvault Auth Bypass Vulnerability

CVE-2025-57788 Overview

CVE-2025-57788 is an authentication bypass vulnerability in Commvault that allows unauthenticated attackers to execute API calls without valid user credentials. The flaw stems from a known login mechanism that can be abused to obtain access tokens. Role-Based Access Control (RBAC) limits the scope of what attackers can reach but does not eliminate the underlying risk. The vulnerability is tracked under CWE-259: Use of Hard-coded Password and was disclosed alongside a broader chain of pre-authentication remote code execution issues in Commvault. The Exploit Prediction Scoring System (EPSS) places this issue in the 99th percentile, indicating a high relative likelihood of exploitation activity compared to other CVEs.

Critical Impact

Unauthenticated attackers can reach authenticated API surface in Commvault, enabling reconnaissance and abuse of backup infrastructure when chained with other flaws.

Affected Products

• Commvault (on-premises distributions covered by advisory CV_2025_08_3)
• Commvault CommServe and Web Server components exposing the affected API endpoints
• Deployments without the August 2025 Commvault security patches applied

Discovery Timeline

• 2025-08-20 - CVE-2025-57788 published to the National Vulnerability Database (NVD)
• 2025-09-10 - Last updated in NVD database
• Vendor advisory - Commvault published Security Advisory CV_2025_08_3
• Third-party research - watchTowr Labs documented the issue in Pre-Auth RCE Chains in Commvault

Technical Details for CVE-2025-57788

Vulnerability Analysis

The vulnerability exists in a known login mechanism inside the Commvault application stack. An unauthenticated attacker reaching the affected endpoint can obtain a valid authentication context without supplying legitimate user credentials. Once authenticated, the attacker can invoke API endpoints normally reserved for logged-in users. RBAC reduces but does not eliminate exposure, because attackers still receive a token usable against any operation accessible to the assumed identity. Security researchers at watchTowr Labs documented the flaw as part of a pre-authentication remote code execution chain, where this bypass serves as the entry point for further exploitation against backup infrastructure.

Root Cause

The root cause is mapped to CWE-259, which covers the use of hard-coded credentials embedded in the product. Static credentials present in the login flow allow any caller with network access to the management interface to authenticate. Because the credentials are fixed in the product distribution, every unpatched instance shares the same weakness. Researchers describe this as a recurrence of credential-handling issues previously identified in the same product family.

Attack Vector

Exploitation requires only network access to the Commvault management interface. No user interaction is needed, and no prior authentication is required. After obtaining an authenticated session through the bypass, attackers can enumerate backup jobs, query configuration, and reach additional API surface. When combined with other Commvault vulnerabilities disclosed in the same advisory cycle, the bypass enables pre-authentication remote code execution against the Commvault server. Detailed technical analysis is available in the watchTowr Labs writeup.

No verified public proof-of-concept code is included in this article. Refer to the Commvault Security Advisory CV_2025_08_3 and the watchTowr research for the technical mechanics of the login bypass.

Detection Methods for CVE-2025-57788

Indicators of Compromise

• Unexpected successful authentication events on Commvault Web Server logs originating from external or unusual internal IP addresses
• API calls to administrative endpoints without a preceding interactive login by a known user account
• Creation of new Commvault users, roles, or storage targets outside of approved change windows
• Outbound connections from the Commvault host to attacker-controlled infrastructure following anomalous API activity

Detection Strategies

• Audit Commvault authentication logs for sessions tied to the known login mechanism described in advisory CV_2025_08_3
• Correlate web server access logs with internal change records to identify API calls that have no corresponding interactive user activity
• Hunt for sequences where unauthenticated requests are followed by privileged API operations against backup jobs or credential vaults

Monitoring Recommendations

• Forward Commvault application, IIS, and Tomcat logs to a central SIEM and retain them for incident response
• Alert on first-seen source IP addresses authenticating to the Commvault management interface
• Monitor for anomalous backup, restore, or export operations that could indicate data exfiltration through the backup tier

How to Mitigate CVE-2025-57788

Immediate Actions Required

• Apply the Commvault patches referenced in Security Advisory CV_2025_08_3 to all CommServe and Web Server instances
• Restrict network access to the Commvault management interface so that only administrative networks can reach it
• Review Commvault user, role, and credential inventories for unauthorized changes since August 2025
• Rotate any credentials or API tokens stored within Commvault that may have been exposed through unauthorized API access

Patch Information

Commvault has released fixed builds addressed in advisory CV_2025_08_3. Administrators should consult the official advisory for the exact patched versions matching their deployment and apply them across all Commvault tiers, including CommServe, MediaAgents, and Web Servers exposing API endpoints.

Workarounds

• Place the Commvault management interface behind a VPN or jump host until patches are applied
• Block external access to Commvault HTTP and HTTPS ports at the perimeter firewall
• Enable enhanced logging on the Commvault Web Server to capture authentication events for later forensic review
• Disable any unused remote API surfaces in line with Commvault hardening guidance