CVE-2025-46603 Overview
CVE-2025-46603 affects Dell CloudBoost Virtual Appliance versions 19.13.0.0 and prior. The flaw is an Improper Restriction of Excessive Authentication Attempts weakness [CWE-307]. An unauthenticated remote attacker can repeatedly submit authentication requests without lockout, throttling, or progressive delay. Successful exploitation can lead to unauthorized access to the appliance through credential guessing or brute-force attacks. Dell published advisory DSA-2025-387 to address the issue along with other vulnerabilities in the same product line.
Critical Impact
Unauthenticated remote attackers can brute-force authentication against the CloudBoost Virtual Appliance, leading to unauthorized access to backup infrastructure and stored data.
Affected Products
- Dell CloudBoost Virtual Appliance versions 19.13.0.0 and prior
- Backup environments integrating CloudBoost with Dell Avamar or NetWorker
- Cloud-tier deployments routing through affected CloudBoost gateways
Discovery Timeline
- 2025-12-05 - CVE-2025-46603 published to NVD
- 2026-01-16 - Last updated in NVD database
Technical Details for CVE-2025-46603
Vulnerability Analysis
The vulnerability stems from missing controls that limit repeated authentication attempts against the CloudBoost Virtual Appliance. Authentication interfaces accept an unbounded number of login requests from the same source, with no lockout policy, no exponential backoff, and no CAPTCHA enforcement. Attackers can iterate through password dictionaries or credential-stuffing lists at machine speed without triggering account suspension.
The weakness aligns with [CWE-307: Improper Restriction of Excessive Authentication Attempts]. Because the attack vector is the network and no privileges or user interaction are required, exploitation can be fully automated using standard HTTP clients. The impact is confidentiality-focused: a successful guess yields valid credentials and access to administrative or service functions of the appliance.
CloudBoost mediates backup traffic between on-premises Dell data protection software and cloud object storage. Unauthorized access to the appliance can expose backup metadata, cloud storage credentials, and configuration controlling data tiering operations.
Root Cause
The root cause is the absence of rate-limiting and account-lockout logic on the authentication handler. The system does not track failed attempts per account or per source address, and it does not enforce delays between attempts.
Attack Vector
An unauthenticated attacker with network reachability to the CloudBoost management interface issues a high volume of authentication requests against a known or enumerated username. With no lockout or throttling in place, the attacker continues until a valid credential is found or the dictionary is exhausted. No phishing, social engineering, or local access is required.
No public proof-of-concept code is available, and the EPSS data indicates a low predicted exploitation probability. Refer to the Dell Security Advisory DSA-2025-387 for vendor technical details.
Detection Methods for CVE-2025-46603
Indicators of Compromise
- High volumes of failed authentication events against the CloudBoost management interface from a single source or a small set of sources.
- Successful logins immediately following sustained failed-login bursts to the same account.
- Authentication attempts originating from IP addresses outside expected administrative networks or geographies.
- New or unexpected administrative sessions on CloudBoost appliances during off-hours.
Detection Strategies
- Forward CloudBoost authentication logs to a centralized SIEM and alert when failed-login counts exceed a defined threshold within a short window.
- Correlate failed authentication spikes with subsequent successful logins from the same source IP to identify brute-force success.
- Baseline expected administrator source addresses and alert on logins from unexpected networks.
Monitoring Recommendations
- Enable verbose authentication logging on the CloudBoost appliance and ship logs to a tamper-resistant collector.
- Monitor network flow data for sustained connections to the appliance management ports from external or untrusted segments.
- Review service account activity on integrated Avamar and NetWorker systems for anomalies that may follow appliance compromise.
How to Mitigate CVE-2025-46603
Immediate Actions Required
- Upgrade Dell CloudBoost Virtual Appliance to the fixed version published in DSA-2025-387.
- Rotate all administrative and service account credentials used with the appliance after patching.
- Review authentication logs for evidence of brute-force activity preceding the patch window.
Patch Information
Dell released remediation in advisory DSA-2025-387, which covers CVE-2025-46603 and other vulnerabilities in CloudBoost Virtual Appliance versions 19.13.0.0 and prior. Apply the vendor-provided update following Dell's documented upgrade procedure. Confirm the appliance reports a fixed version after the upgrade completes.
Workarounds
- Restrict network access to the CloudBoost management interface using firewall rules, allowing connections only from designated administrative subnets.
- Place the appliance behind a VPN or jump host that enforces multi-factor authentication and lockout policies upstream.
- Enforce long, unique passwords for all CloudBoost accounts to reduce the success rate of dictionary attacks while patching is scheduled.
- Disable or remove unused local accounts on the appliance to reduce the attack surface.
# Example: restrict access to CloudBoost management interface to a trusted admin subnet
iptables -A INPUT -p tcp --dport 443 -s 10.10.50.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
