CVE-2025-61029: Virtuoso Open-Source DoS Vulnerability

CVE-2025-61029 Overview

CVE-2025-61029 is a denial-of-service vulnerability in the sqlo_untry component of OpenLink virtuoso-opensource version 7.2.11. Attackers can crash the database server by submitting crafted SQL statements over the network. The flaw is classified under [CWE-89] and requires no authentication or user interaction. Exploitation impacts availability only, with no confidentiality or integrity exposure. The issue is tracked publicly in the project's GitHub issue tracker.

Critical Impact
An unauthenticated, remote attacker can trigger a denial-of-service condition against Virtuoso 7.2.11 by sending a crafted SQL statement to the sqlo_untry component.

Affected Products

OpenLink virtuoso-opensource v7.2.11
The sqlo_untry SQL optimizer component
Deployments exposing the Virtuoso SQL interface to untrusted networks

Discovery Timeline

2026-06-23 - CVE-2025-61029 published to NVD
2026-06-23 - Last updated in NVD database

Technical Details for CVE-2025-61029

Vulnerability Analysis

The vulnerability resides in the sqlo_untry routine within Virtuoso's SQL optimizer subsystem. When the server parses and attempts to optimize a malformed or specifically crafted SQL statement, processing inside sqlo_untry reaches an error state that terminates the server process. Because Virtuoso typically runs as a long-lived daemon handling many concurrent client connections, a single malicious statement can disrupt service for all users.

The issue is associated with [CWE-89] (SQL Injection) in the NVD record, but the practical impact reported in the upstream GitHub issue is process termination rather than data manipulation. Attackers send the trigger payload through any interface that reaches the SQL parser, including the native SQL listener and ODBC or JDBC clients.

Root Cause

The root cause is insufficient validation of input structures inside sqlo_untry during query optimization. The function does not safely handle the unexpected parser state produced by the crafted statement, leading to an unrecoverable condition. Refer to the GitHub Issue Discussion for the reproducer and maintainer comments.

Attack Vector

The attack vector is network-based with low complexity and no privileges required. An attacker authenticates or connects anonymously to the Virtuoso SQL endpoint and submits the crafted SQL statement. The server process crashes, terminating all active sessions and requiring a restart to restore service.

// No verified proof-of-concept code is available.
// See the upstream GitHub issue for reproduction details:
// https://github.com/openlink/virtuoso-opensource/issues/1228

Detection Methods for CVE-2025-61029

Indicators of Compromise

Unexpected termination or repeated restarts of the virtuoso-t daemon process
SQL listener connections immediately preceding a process crash in server logs
Spikes of malformed SQL parse errors followed by service unavailability

Detection Strategies

Monitor Virtuoso server logs for parser exceptions referencing the optimizer or sqlo_untry code paths.
Alert on abnormal process exit codes or core dumps for the Virtuoso service.
Correlate client source IP addresses with SQL parse failures to identify probing behavior.

Monitoring Recommendations

Track service uptime and restart counts for Virtuoso instances exposed to untrusted networks.
Forward database and host telemetry to a centralized analytics platform for cross-source correlation.
Apply network access controls and log all client sessions reaching the SQL listener port.

How to Mitigate CVE-2025-61029

Immediate Actions Required

Restrict network access to Virtuoso SQL listener ports to trusted application hosts only.
Require authentication for all SQL connections and remove anonymous access where present.
Enable automatic service restart so that crashes do not cause prolonged outages while a fix is pending.

Patch Information

No official patch version is referenced in the NVD record at the time of publication. Track the GitHub Issue Discussion and the openlink/virtuoso-opensource repository for a fixed release beyond version 7.2.11.

Workarounds

Place Virtuoso behind a SQL-aware proxy or firewall that filters malformed statements.
Limit which database accounts can issue ad hoc SQL and restrict optimizer-heavy query patterns.
Run Virtuoso under a process supervisor such as systemd with Restart=on-failure to reduce downtime.

bash

# Example systemd override to auto-restart Virtuoso on crash
sudo systemctl edit virtuoso-opensource.service
# Add the following content:
# [Service]
# Restart=on-failure
# RestartSec=5s
sudo systemctl daemon-reload
sudo systemctl restart virtuoso-opensource.service