External risk intelligence

ClickHouse Server SQL Injection Vulnerability Allows Arbitrary Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-51992

ClickHouse is a database management system. While database servers are typically deployed within internal, protected network segments and not directly exposed to the public internet, they are occasionally exposed in specific configurations or as part of managed service architectures, making internet reachability possible but not the default or intended deployment pattern.

SQL Injection

Halo Surface Signal: 3 out of 5 — possibly public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical SQL injection vulnerability has been identified in ClickHouse Server, a database management system. This flaw could allow an unauthorized remote attacker to execute arbitrary code, posing a significant risk to data integrity and system security if exploited. The main concern is confirming relevance and exposure within our environment.

A database code-execution flaw exists.
Protects data and critical system functions.
Confirm if ClickHouse is used internally.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by sending specially crafted SQL queries to a ClickHouse server over the network. If the server processes these queries through its "create dictionaries" function without properly sanitizing the input, the attacker might be able to inject malicious SQL code. This could lead to the execution of arbitrary commands on the server.

No authentication required.
Via the create dictionaries function.
Remote code execution.

Live Threat

Current exploitation, exposure, and threat context

A SQL injection vulnerability in ClickHouse Server could allow a remote attacker to execute arbitrary code through the `create dictionaries` function. This could impact system data and service behavior when supported by the advisory.

System data and configuration.
Exploitation via specially crafted SQL queries.
Arbitrary code execution.

Operational Fix

Recommended remediation, mitigation, and detection steps

ClickHouse Server instances are likely managed by database administration or platform teams, with potential oversight from security and network teams. The first practical step is to identify all ClickHouse deployments, confirm their internet reachability and business criticality, and then engage the accountable owners to plan remediation based on risk.

Database or platform teams own this.
Verify internet-facing instances first.
Plan risk-based remediation actions.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is ClickHouse Server?

ClickHouse is an open-source, high-performance column-oriented database management system. It is designed to process massive volumes of analytical data in real-time, allowing users to run complex queries across billions of rows. Because it handles large-scale data processing for applications and analytics platforms, it is often a central piece of data infrastructure that requires stable and secure connectivity to function effectively.

What is the nature of the CVE-2026-51992 vulnerability?

This vulnerability is classified as a SQL Injection (CWE-89) weakness. In plain terms, it means the server's input processing logic does not properly isolate user-provided data from executable commands. By submitting malicious SQL queries, an attacker can trick the system into running unauthorized code instead of simply retrieving data, essentially bypassing the intended boundaries of the database's command structure.

How can an attacker trigger this vulnerability?

An attacker exploits this flaw by interacting with the 'create dictionaries' function in ClickHouse Server. The issue occurs when this function processes a specially crafted SQL query without sufficient sanitization. It is important to note that this flaw does not require the attacker to have pre-existing credentials or authentication; however, the vulnerability is not triggered by standard read-only queries or interactions that do not utilize this specific dictionary-creation mechanism.

Do I need to worry if my ClickHouse instance is internal?

While database servers are typically kept behind firewalls, Halo Surface Signal notes that internet reachability is possible depending on your specific network configuration or managed service setup. Even if a system is not public-facing, it remains at risk if an attacker gains access to your internal network. You should treat any instance that could be reached by unauthorized parties as a potential concern.

What is the first step to address CVE-2026-51992?

Start by identifying every instance of ClickHouse running within your environment to understand your total footprint. Once you have a list of deployments, determine which ones are accessible over the network and prioritize them based on their business criticality. Coordinate with the teams managing these databases to plan for updates, ensuring that remediation is handled systematically to maintain both security and system availability.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.