CVE-2007-0556 in PostgreSQL
Summary
by MITRE
The query planner in PostgreSQL before 8.0.11, 8.1 before 8.1.7, and 8.2 before 8.2.2 does not verify that a table is compatible with a "previously made query plan," which allows remote authenticated users to cause a denial of service (server crash) and possibly access database content via an "ALTER COLUMN TYPE" SQL statement, which can be leveraged to read arbitrary memory from the server.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/14/2019
The vulnerability described in CVE-2007-0556 represents a critical flaw in PostgreSQL's query planning mechanism that affects multiple versions including 8.0.10 and earlier, 8.1.6 and earlier, and 8.2.1 and earlier. This issue stems from insufficient validation within the query planner component that manages how SQL queries are executed and optimized. The flaw specifically occurs when the system fails to properly verify table compatibility with previously cached query plans, creating a scenario where malicious actors can exploit this weakness through carefully crafted ALTER COLUMN TYPE statements.
The technical exploitation of this vulnerability involves a sophisticated attack pattern that leverages the database's query plan caching system. When PostgreSQL executes queries, it creates and caches optimized execution plans to improve performance. However, in the affected versions, the system does not adequately validate whether the current table structure remains compatible with previously generated plans. This oversight allows attackers to manipulate table schemas through ALTER COLUMN TYPE commands while simultaneously triggering the execution of cached plans that were designed for different table structures, leading to memory corruption and system instability.
The operational impact of this vulnerability extends beyond simple denial of service to potentially expose sensitive database content. Remote authenticated users can leverage this weakness to cause server crashes through controlled memory access patterns, but more concerning is the potential for arbitrary memory reading that could expose confidential database information. This represents a significant security risk as attackers can potentially extract sensitive data from the database server, making the vulnerability particularly dangerous in environments where database integrity and confidentiality are paramount. The vulnerability aligns with CWE-129, which addresses improper validation of array indices, and relates to ATT&CK technique T1499.004 for network denial of service, though it also encompasses data exposure aspects.
Mitigation strategies for this vulnerability require immediate patching of affected PostgreSQL versions to the recommended secure releases including 8.0.11, 8.1.7, and 8.2.2. Organizations should implement comprehensive monitoring to detect unusual ALTER COLUMN TYPE operations and establish strict access controls to limit who can execute such commands. Additionally, database administrators should consider implementing query plan invalidation procedures that automatically clear cached plans when table structures are modified, preventing the exploitation of cached plan compatibility issues. The vulnerability demonstrates the critical importance of maintaining up-to-date database systems and implementing proper input validation and plan verification mechanisms to prevent similar issues in future deployments.