CVE-2018-10925 in PostgreSQL
Summary
by MITRE
It was discovered that PostgreSQL versions before 10.5, 9.6.10, 9.5.14, 9.4.19, and 9.3.24 failed to properly check authorization on certain statements involved with "INSERT ... ON CONFLICT DO UPDATE". An attacker with "CREATE TABLE" privileges could exploit this to read arbitrary bytes server memory. If the attacker also had certain "INSERT" and limited "UPDATE" privileges to a particular table, they could exploit this to update other columns in the same table.
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Analysis
by VulDB Data Team • 05/01/2023
The vulnerability identified as CVE-2018-10925 represents a critical authorization bypass flaw within PostgreSQL database management systems affecting multiple version branches including 10.5, 9.6.10, 9.5.14, 9.4.19, and 9.3.24. This security issue stems from insufficient validation of user permissions during specific database operations involving the INSERT ... ON CONFLICT DO UPDATE statement syntax. The flaw manifests when the database fails to properly verify that users possess adequate privileges before executing certain memory-access operations, creating a pathway for unauthorized data access and modification. The vulnerability is particularly concerning because it allows attackers to escalate their privileges through a combination of CREATE TABLE rights and specific INSERT and UPDATE permissions on target tables, demonstrating a significant weakness in PostgreSQL's access control mechanisms.
The technical implementation of this vulnerability occurs within the PostgreSQL query processing engine where the authorization checks for the ON CONFLICT DO UPDATE clause are inadequately enforced. When a user executes an INSERT ... ON CONFLICT DO UPDATE statement, the system should validate that the user has appropriate permissions to both insert data and update existing records in the target table. However, the flaw allows attackers with CREATE TABLE privileges to manipulate the query execution flow in such a way that they can read arbitrary memory contents from the database server. This memory disclosure occurs because the authorization checks are bypassed during specific conditions within the conflict resolution process, enabling attackers to potentially extract sensitive information including database credentials, connection details, and other confidential data stored in server memory. The vulnerability falls under CWE-284 which specifically addresses insufficient access control mechanisms, and aligns with ATT&CK technique T1078 for valid accounts and T1566 for credential access through exploitation of database vulnerabilities.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to perform unauthorized data modification operations when combined with appropriate privilege levels. An attacker with CREATE TABLE permissions can leverage this flaw to read memory contents that may contain database connection strings, encryption keys, or other sensitive information that could be used for further exploitation. When combined with INSERT and limited UPDATE privileges on specific tables, the vulnerability becomes even more dangerous as attackers can modify data within the same table, potentially leading to data corruption, privilege escalation, or unauthorized transaction manipulation. The memory access issue creates a potential for data exfiltration attacks where attackers can harvest sensitive information from the database server's memory space. Organizations using affected PostgreSQL versions face significant risk of unauthorized data access and modification, with the vulnerability being particularly dangerous in environments where database administrators maintain multiple privilege levels and complex access control policies. The flaw demonstrates how seemingly minor authorization check gaps can lead to substantial security breaches, making it a critical concern for database administrators and security teams responsible for protecting enterprise data assets. Mitigation requires immediate patching of affected PostgreSQL versions to ensure proper authorization validation during conflict resolution operations, along with careful monitoring of database access patterns and privilege assignments to prevent exploitation attempts.