Address CVE-2025-59250: Fix spoofing vulnerability in JDBC Driver for SQL Server due to improper input validation and update version to 12.6.5

[Ananya2]

This PR includes:

• Addressing CVE-2025-59250: JDBC Driver for SQL Server Spoofing Vulnerability: Improper input validation in JDBC Driver for SQL Server allows an unauthorized attacker to perform spoofing over a network.
• Version updates to 12.6.5

Problem Statement

The MSSQL JDBC driver's SSL certificate validation contains a critical security vulnerability that allows hostname spoofing attacks. The current parseCommonName() method uses unsafe string parsing on the "canonical" format of X.509 Distinguished Names, which can be exploited by malicious certificates.

Security Impact

An attacker can craft malicious X.509 certificates that bypass hostname validation by embedding fake hostnames within other certificate attributes. This allows man-in-the-middle attacks where:

Attacker presents a certificate with DN like: OU=CN=legitimate-server.com, CN=attacker.com
The vulnerable parser incorrectly extracts legitimate-server.com instead of the actual CN attacker.com
Application accepts the certificate as valid for legitimate-server.com when it's actually issued for attacker.com
SSL/TLS connection proceeds with compromised security

Root Cause Analysis

Unsafe String Parsing: Original code used indexOf("cn=") and substring operations on the "canonical" DN format
Format Ambiguities: The "canonical" format lowercases and reverses RDN order, creating parsing ambiguities
Insufficient Validation: No proper escaping/unescaping of DN components
Regex Vulnerabilities: Simple pattern matching vulnerable to DN injection attacks

Solution

Complete rewrite of CN parsing logic using secure, industry-standard approaches:

Secure DN Parsing:

Replaced custom string parsing with javax.naming.ldap.LdapName and Rdn classes
Uses RFC2253 format instead of vulnerable "canonical" format
Proper handling of escaped characters and DN structure

Security Testing:

Added testSecureCNParsing_preventsHostnameSpoofing() test case
Validates fix prevents known attack vectors
Mock certificate testing framework for edge cases