CVE-2025-1386 Overview
CVE-2025-1386 is an HTTP Request Smuggling vulnerability affecting the ClickHouse ch-go library, a Go client for ClickHouse databases. When using this library under specific conditions involving queries with large, uncompressed malicious external data, an attacker who controls such data can smuggle additional query packets into the connection stream. This vulnerability falls under CWE-444 (Inconsistent Interpretation of HTTP Requests), which relates to HTTP Request Smuggling attacks.
Critical Impact
Attackers with high privileges who control external data inputs can inject unauthorized queries into the database connection stream, potentially leading to unauthorized data access or manipulation of ClickHouse database operations.
Affected Products
- ClickHouse ch-go library for Go
- Applications using the ch-go library with external data functionality
- ClickHouse database deployments utilizing the vulnerable ch-go client versions
Discovery Timeline
- April 11, 2025 - CVE-2025-1386 published to NVD
- December 19, 2025 - Last updated in NVD database
Technical Details for CVE-2025-1386
Vulnerability Analysis
This vulnerability exists in the ch-go library's handling of external data within query requests. The issue stems from improper parsing and boundary handling when processing large, uncompressed external data payloads. Under specific conditions, the library fails to properly delineate query boundaries, allowing an attacker to inject additional query packets into the established connection stream.
HTTP Request Smuggling vulnerabilities like this one occur when there is inconsistent interpretation of HTTP request boundaries between different components in the request processing pipeline. In this case, the ch-go library's connection handling mechanism can be exploited when malicious external data is crafted to contain embedded query structures that bypass normal query parsing.
The attack requires network access and high privileges, but does not require user interaction. Successful exploitation could result in high confidentiality impact, allowing attackers to access sensitive data by executing unauthorized queries against the ClickHouse database.
Root Cause
The root cause is improper handling of request boundaries in the ch-go library when processing external data within queries. The library does not adequately validate or sanitize large uncompressed external data inputs, creating a condition where query packet boundaries become ambiguous. This allows malicious payloads to be interpreted as separate query packets rather than data content.
Attack Vector
The attack vector is network-based and requires an attacker with high privileges who can control external data inputs to queries executed through the ch-go library. The attacker must craft malicious external data that, when included in a query, causes the library to misinterpret packet boundaries. This results in the smuggled query being executed as a separate, legitimate query on the ClickHouse database connection.
The exploitation process involves:
- Identifying an application using the vulnerable ch-go library that accepts external data inputs
- Crafting a large, uncompressed external data payload containing embedded query structures
- Submitting the malicious payload through normal query channels
- The library misparses the boundaries, executing the smuggled query
For detailed technical information about this vulnerability, refer to the GitHub Security Advisory.
Detection Methods for CVE-2025-1386
Indicators of Compromise
- Unusual or unexpected queries appearing in ClickHouse query logs
- Large external data payloads in query requests that exceed normal operational patterns
- Database operations occurring that do not correspond to legitimate application activity
- Anomalous connection behavior or multiple queries executed within single connection sessions
Detection Strategies
- Monitor ClickHouse query logs for unauthorized or unexpected query patterns
- Implement application-level logging to track external data sizes and sources
- Deploy network monitoring to detect abnormally large query payloads to ClickHouse instances
- Review database audit logs for queries executed with unexpected timing or content
Monitoring Recommendations
- Enable comprehensive query logging on ClickHouse servers
- Implement alerting for queries exceeding normal size thresholds for external data
- Monitor ch-go library versions in use across applications and flag vulnerable deployments
- Establish baseline query patterns and alert on deviations that may indicate smuggling attempts
How to Mitigate CVE-2025-1386
Immediate Actions Required
- Audit all applications using the ch-go library to identify vulnerable deployments
- Restrict external data functionality to trusted sources only until patches are applied
- Implement input validation and size limits on external data inputs at the application layer
- Review ClickHouse access controls to ensure principle of least privilege
Patch Information
Refer to the GitHub Security Advisory for the latest patched version of the ch-go library. Upgrading to the patched version is the recommended remediation. Organizations should update their Go module dependencies to incorporate the fixed ch-go library version.
Workarounds
- Disable or restrict external data functionality in queries where possible
- Implement strict input validation on all external data before passing to ch-go
- Apply network-level controls to limit access to ClickHouse instances from untrusted sources
- Consider implementing query allowlists or query analysis middleware to detect anomalous patterns
# Configuration example - Update go.mod to latest ch-go version
go get github.com/ClickHouse/ch-go@latest
go mod tidy
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
