CVE-2026-42100: Sparx Pro Cloud Server DoS Vulnerability

CVE-2026-42100 Overview

CVE-2026-42100 is a denial of service vulnerability in Sparx Pro Cloud Server caused by improper handling of syntactically invalid SQL structures [CWE-228]. An authenticated attacker can send a specially crafted SQL query that triggers an unexpected termination of the Pro Cloud Server service. Version 6.1 (build 167) and earlier are confirmed vulnerable, and untested versions may also be affected.

The vendor was notified early but did not respond with the details of the vulnerability or the vulnerable version range. The flaw is network-reachable and requires only low-privilege access to exploit.

Critical Impact

Authenticated remote attackers can terminate the Pro Cloud Server service by submitting a malformed SQL query, disrupting modeling and collaboration workflows for all connected users.

Affected Products

• Sparx Pro Cloud Server version 6.1 (build 167)
• Sparx Pro Cloud Server versions below 6.1 (build 167)
• Other versions are untested and may also be vulnerable

Discovery Timeline

• 2026-05-19 - CVE-2026-42100 published to NVD
• 2026-05-19 - Last updated in NVD database

Technical Details for CVE-2026-42100

Vulnerability Analysis

The Pro Cloud Server exposes a SQL query interface used by Sparx Enterprise Architect clients to interact with backend model repositories. The server fails to validate the syntactic structure of incoming SQL statements before passing them into its query handling pipeline. A malformed query causes the parser to enter an unrecoverable state, terminating the service process.

Because the Pro Cloud Server brokers access for all connected modeling clients, a single crafted request disrupts collaboration for every user of the instance. The service must be restarted manually or by a watchdog to restore availability, and unsaved client work may be lost during the outage.

Root Cause

The root cause is improper handling of a syntactically invalid structure [CWE-228] inside the SQL processing path of Pro Cloud Server. The service does not sanitize or reject malformed query syntax before dispatching it to lower-level handlers, leading to an unhandled error condition and abrupt process termination.

Attack Vector

The attack vector is network-based and requires low-privileged authenticated access to the Pro Cloud Server. An attacker with valid credentials submits a specially crafted SQL query through the standard client interface. No user interaction is required, and exploitation does not affect confidentiality or integrity, but it fully eliminates availability of the service.

The vulnerability mechanism is described in prose only. No verified proof-of-concept code is available in the public references. Refer to the Sploit Tech Sparx Architect Analysis and the Efigo Blog CVE-2026-42096 writeup for additional technical context.

Detection Methods for CVE-2026-42100

Indicators of Compromise

• Unexpected termination of the Pro Cloud Server service process on the host
• Application or Windows event log entries showing crash, access violation, or unhandled exception in the Pro Cloud Server binary
• Sudden disconnections of all Sparx Enterprise Architect clients connected to the same server instance
• Malformed SQL statements in Pro Cloud Server query logs preceding a crash

Detection Strategies

• Correlate Pro Cloud Server process exit events with authenticated session activity from the same time window to identify the requesting account
• Inspect application logs for SQL parse errors or stack traces immediately before service termination
• Alert on repeated unplanned restarts of the Pro Cloud Server service within short intervals

Monitoring Recommendations

• Forward Pro Cloud Server application and crash logs to a central SIEM or data lake for retention and query
• Monitor authentication events against Pro Cloud Server to identify low-privilege accounts that submit malformed queries
• Track service uptime metrics and alert when availability falls below baseline thresholds

How to Mitigate CVE-2026-42100

Immediate Actions Required

• Inventory all Sparx Pro Cloud Server deployments and identify hosts running version 6.1 (build 167) or earlier
• Restrict network access to the Pro Cloud Server to trusted client subnets using firewall rules or VPN segmentation
• Audit and reduce the number of low-privilege accounts that can submit queries to the server
• Enable automatic service recovery so the Pro Cloud Server restarts after an unexpected termination

Patch Information

No vendor patch has been published in the referenced advisories at the time of disclosure. The vendor was notified early but did not respond with a vulnerable version range or remediation guidance. Monitor the Sparx Systems ProCloudServer Overview page and the CERT.pl CVE-2026-42096 Advisory for updates.

Workarounds

• Place the Pro Cloud Server behind a reverse proxy or query filter that rejects malformed SQL syntax before it reaches the service
• Limit account privileges so that only vetted users can connect to the model repository
• Configure the Pro Cloud Server service for automatic restart on failure to minimize downtime from successful exploitation
• Snapshot the Pro Cloud Server host regularly to support rapid recovery if abuse occurs

# Configure automatic restart on Windows for the Pro Cloud Server service
sc.exe failure "Sparx Systems Professional Cloud" reset= 60 actions= restart/5000/restart/5000/restart/5000
sc.exe failureflag "Sparx Systems Professional Cloud" 1