CVE-2026-23969: 
Apache Superset vulnerability analysis and mitigation

CVE-2026-23969 is an information disclosure vulnerability in Apache Superset titled "Exposure of Sensitive Information via Incomplete ClickHouse Function Filtering." It affects all versions of Apache Superset before 4.1.2 and stems from an incomplete DISALLOWED_SQL_FUNCTIONS blocklist for the ClickHouse database engine, allowing authenticated users to invoke restricted SQL functions. The vulnerability was publicly disclosed on February 24, 2026, by Daniel Gaspar of the Apache Superset project, with credit to reporter Saif Salah. It carries a CVSS v3.1 base score of 6.5 (Medium/High) and a CVSS v4.0 base score of 5.3 (Medium) (Apache OSS-Security, Red Hat CVE).

The root cause is classified as CWE-89 (Improper Neutralization of Special Elements used in an SQL Command / SQL Injection), arising from an incomplete denylist configuration rather than a code-level injection flaw. Apache Superset uses the DISALLOWED_SQL_FUNCTIONS dictionary to block sensitive SQL functions in SQL Lab and chart queries; while engines like PostgreSQL had adequate entries, the ClickHouse engine's default list was missing entries for potentially sensitive functions. An authenticated, low-privileged user can exploit this by crafting SQL queries in SQL Lab or charts that invoke ClickHouse functions not present in the blocklist, bypassing the intended access control. No public proof-of-concept exploit code has been identified at this time (Apache OSS-Security, Red Hat CVE).

Successful exploitation allows an authenticated attacker to execute sensitive ClickHouse SQL functions that should be restricted, leading to unauthorized exposure of sensitive information (high confidentiality impact). There is no integrity or availability impact associated with this vulnerability. The scope is limited to the Superset instance and its connected ClickHouse data sources; however, depending on the data accessible via ClickHouse, this could expose business-critical or personally identifiable information (Apache OSS-Security, Red Hat CVE).

1. Reconnaissance: Identify an Apache Superset instance (version < 4.1.2) that is connected to a ClickHouse database engine, accessible via the web interface.
2. Authentication: Log in to Apache Superset with any valid low-privileged user account that has access to SQL Lab or chart creation.
3. Identify unrestricted functions: In SQL Lab, craft SQL queries targeting the ClickHouse connection and attempt to invoke sensitive ClickHouse-specific SQL functions (e.g., file-reading or system-information functions) that are absent from the DISALLOWED_SQL_FUNCTIONS blocklist.
4. Execute restricted query: Submit the crafted SQL query against the ClickHouse data source; because the function is not in the blocklist, Superset forwards the query to ClickHouse without restriction.
5. Exfiltrate data: Review the query results returned in SQL Lab or chart output to access sensitive information exposed by the unrestricted function (Apache OSS-Security).

• Logs: Apache Superset query audit logs showing SQL Lab or chart queries from low-privileged users invoking ClickHouse-specific sensitive functions (e.g., file(), url(), remoteSecure(), or similar system/network functions) against ClickHouse data sources.
• Network: Unexpected outbound connections from the ClickHouse server to external hosts, which may indicate exploitation of network-accessing ClickHouse functions.
• Application: Repeated SQL Lab query submissions by a single user account targeting ClickHouse connections with unusual or system-level function calls.

The primary remediation is to upgrade Apache Superset to version 4.1.2 or later, which includes an updated DISALLOWED_SQL_FUNCTIONS list with complete ClickHouse engine entries. As a workaround prior to upgrading, administrators can manually extend the DISALLOWED_SQL_FUNCTIONS configuration in superset_config.py to include sensitive ClickHouse functions relevant to their environment. Restricting SQL Lab and chart access to trusted users only can also reduce exposure risk (Apache OSS-Security, Red Hat CVE).

Security Online Info covered the vulnerability as part of a broader report on five Apache Superset vulnerabilities patched in the same release cycle, noting the significance of the security overhaul (Security Online). The disclosure was made via the Apache mailing list and oss-security by Daniel Gaspar, with credit to reporter Saif Salah, following standard coordinated disclosure practices. Community reaction has been limited, with no notable controversy or widespread social media discussion observed.