CVE-2009-2940 in pygresql
Summary
by MITRE
The pygresql module 3.8.1 and 4.0 for Python does not properly support the PQescapeStringConn function, which might allow remote attackers to leverage escaping issues involving multibyte character encodings.
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Analysis
by VulDB Data Team • 03/25/2025
The pygresql module version 3.8.1 and 4.0 for Python contains a critical vulnerability in its handling of the PQescapeStringConn function that can lead to improper escaping of multibyte character encodings. This flaw exists within the PostgreSQL database adapter implementation that is used to connect Python applications to PostgreSQL databases. The vulnerability stems from inadequate processing of character encoding transformations during database query construction, particularly when dealing with international character sets that require multibyte representations. Attackers can exploit this weakness to manipulate database queries through specially crafted input that leverages the improper escaping behavior. The issue is particularly concerning because it affects the fundamental data sanitization mechanisms that protect against injection attacks in database communications.
This vulnerability represents a classic case of insufficient input validation and escaping mechanisms within database connectivity libraries. The flaw allows attackers to bypass normal query parameterization and input sanitization by exploiting how the PQescapeStringConn function handles character encodings. When multibyte characters are processed through the flawed escaping routine, the encoding transformations can introduce unexpected behavior that permits malicious input to be interpreted as part of the database query rather than as literal data. The vulnerability is categorized under CWE-119 which addresses improper restriction of operations within a limited access scope, and more specifically relates to CWE-77 which covers command and query injection flaws. This weakness enables attackers to perform unauthorized database operations through carefully constructed payloads that exploit the encoding handling issues.
The operational impact of this vulnerability extends beyond simple data manipulation to potentially allow full database compromise. Remote attackers can leverage the escaping issues to inject malicious SQL commands that bypass normal security controls, potentially leading to unauthorized data access, modification, or deletion. The vulnerability affects any Python application that uses the pygresql module to connect to PostgreSQL databases and relies on proper escaping of user inputs. Attackers can craft inputs containing specific multibyte character sequences that, when processed through the flawed PQescapeStringConn function, result in query injection opportunities. This creates a significant risk for applications handling sensitive data where database security is paramount, as the vulnerability can be exploited without requiring special privileges or extensive reconnaissance.
Mitigation strategies for this vulnerability involve immediate patching of the pygresql module to version 4.1 or later, which contains the necessary fixes for the PQescapeStringConn function handling. Organizations should also implement additional input validation layers in their applications to reduce the impact of any potential exploitation attempts. Database administrators should review and tighten access controls, ensuring that applications use minimal required privileges and that proper parameterized queries are implemented at the application level. Security monitoring should be enhanced to detect unusual database access patterns that might indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1071.004 for application layer protocol and T1566 for credential access through privilege escalation. Organizations should also consider implementing web application firewalls and database activity monitoring solutions to provide additional protection layers against exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar issues in other database connectivity libraries within the application stack.