CVE-2026-13739: Command Center SSRF Vulnerability

CVE-2026-13739 Overview

CVE-2026-13739 is an unauthenticated server-side request forgery (SSRF) vulnerability in a legacy endpoint of Commvault Command Center. The flaw stems from unsafe handling of arbitrary target URLs, allowing a remote attacker to coerce the Command Center server into issuing HTTP requests to attacker-chosen destinations. Because the endpoint requires no authentication, exploitation can be performed by any network-adjacent attacker who can reach the Command Center web interface. Commvault has published advisory CV_2026_07_5 and released a maintenance update that resolves the issue.

Critical Impact
An unauthenticated remote attacker can force Command Center to make arbitrary HTTP requests, enabling internal network reconnaissance, access to cloud metadata services, and interaction with internal-only services otherwise unreachable from the internet.

Affected Products

Commvault Command Center (legacy endpoint, versions prior to the resolved maintenance release)
Deployments exposing Command Center to untrusted networks
On-premises Commvault installations that have not applied the CV_2026_07_5 maintenance update

Discovery Timeline

2026-08-11 - CVE-2026-13739 published to NVD
2026-08-11 - Last updated in NVD database

Technical Details for CVE-2026-13739

Vulnerability Analysis

The vulnerability is a server-side request forgery [CWE-918] in a legacy Command Center endpoint. The endpoint accepts a target URL parameter and issues an outbound HTTP request from the server without validating the destination against an allowlist or blocking internal address ranges. Because no authentication is enforced, an attacker with only network reachability to the Command Center interface can drive the server to fetch attacker-specified resources.

The practical impact centers on confidentiality. The response returned to the attacker can expose data from internal services, cloud instance metadata endpoints, and management APIs bound to loopback or internal interfaces. In cloud deployments, SSRF against metadata services frequently yields temporary credentials tied to the Command Center host's identity. Integrity and availability impacts are lower but not zero, as the coerced request can trigger state-changing operations on internal HTTP endpoints that trust the Command Center source address.

Root Cause

The root cause is missing validation of user-controlled URL input in a legacy request-forwarding routine. The endpoint does not enforce a scheme, host, or port allowlist, does not resolve and check destination IP addresses against private and link-local ranges, and does not require authentication before performing the outbound fetch.

Attack Vector

Exploitation occurs over the network and requires no privileges or user interaction. An attacker sends a crafted HTTP request to the vulnerable legacy endpoint with a target URL pointing at an internal resource. Common SSRF targets include cloud metadata endpoints such as 169.254.169.254, loopback-bound admin interfaces on 127.0.0.1, and internal service hostnames reachable only from the Command Center host.

No verified public exploit code is available. See the Commvault Security Advisory CV_2026_07_5 for vendor technical details.

Detection Methods for CVE-2026-13739

Indicators of Compromise

Outbound HTTP requests from the Command Center host to 169.254.169.254, 127.0.0.1, or other RFC1918 addresses that do not match normal application behavior
Web access logs on the Command Center showing unauthenticated requests to the legacy endpoint with URL parameters containing internal hostnames, IP literals, or non-HTTP schemes
Unusual DNS lookups originating from the Command Center service account for external attacker-controlled domains

Detection Strategies

Review Command Center access logs for requests to legacy endpoints containing URL-style query parameters, particularly from unauthenticated sessions
Correlate inbound HTTP requests to Command Center with subsequent outbound connections from the same host to identify request-forwarding patterns
Alert on any Command Center process making direct connections to cloud metadata service IP addresses

Monitoring Recommendations

Enable verbose HTTP access logging on Command Center and forward logs to a centralized analytics platform
Monitor egress traffic from Command Center hosts and baseline expected destinations to detect deviations
Track authentication state on legacy endpoints and flag requests that bypass session validation

How to Mitigate CVE-2026-13739

Immediate Actions Required

Apply the Commvault maintenance release referenced in advisory CV_2026_07_5 to all Command Center installations
Restrict network access to Command Center to trusted administrative networks using firewall or reverse-proxy allowlists
Rotate any cloud instance credentials, API tokens, or service account secrets accessible from the Command Center host if exposure is suspected

Patch Information

Commvault has released a resolved maintenance update for Command Center. Refer to the Commvault Security Advisory CV_2026_07_5 for the specific fixed versions and upgrade instructions. Customers should upgrade to the resolved maintenance release as the primary remediation.

Workarounds

Place Command Center behind a reverse proxy that blocks requests to the vulnerable legacy endpoint until patching is complete
Apply host-based egress filtering to deny outbound connections from the Command Center host to cloud metadata IPs and internal management ranges not required for operation
Where supported, disable or remove the legacy endpoint from the Command Center configuration if the maintenance update cannot be applied immediately

bash

# Example egress restriction using iptables to block cloud metadata access
iptables -A OUTPUT -d 169.254.169.254 -j DROP
iptables -A OUTPUT -d 127.0.0.0/8 -p tcp --dport 8000:9000 -j DROP