A recently identified flaw in Microsoft SQL Server, designated as CVE-2025-49719, presents a significant information disclosure vulnerability that impacts SQL Server versions ranging from 2016 through 2022. This vulnerability allows unauthorized access to uninitialized memory, potentially exposing sensitive data such as credentials and connection strings. The flaw stems from improper input validation within SQL Server’s memory management system, affecting both the SQL Server engine and applications utilizing OLE DB drivers. This vulnerability is classified under CWE-20: Improper Input Validation, which highlights the underlying issue contributing to the risk.
The severity of the vulnerability is underscored by its high CVSSv3 score of 7.5. Additionally, it is categorized as a zero-day vulnerability, having been publicly disclosed prior to any patch being made available. Attackers could exploit this weakness to snoop on sensitive data over networks without the need for authentication or user interaction, thereby broadening its risk across numerous SQL Server deployments. This vulnerability mainly affects SQL Server instances on Windows platforms. Moreover, the need for frequent updates has been emphasized by Microsoft in response to this issue, reinforcing the importance of keeping systems patched against vulnerabilities.
The vulnerability’s high CVSSv3 score of 7.5 highlights its risk, enabling unauthorized data access without authentication across SQL Server instances.
Microsoft’s response to this critical issue included the release of security updates on July 8, 2025, during its Patch Tuesday cycle, addressing a total of 130 vulnerabilities, including CVE-2025-49719. These updates rectify both the initial flaw and related connectivity issues identified in the SQL Server Native Client. The corrective measures focus on preventing unauthorized access to uninitialized memory and rectifying input validation processes.
Technical analysis of the exploitation mechanism reveals that attackers may utilize improper handling of variable-length parameters and query execution procedures to induce SQL Server to reveal memory contents. Although specific residual data leaks from heap-based memory are possible, there have been no indications of direct remote code execution or privilege escalation from this vulnerability.
The patch’s release coincided with the rectification of additional critical vulnerabilities across Microsoft products, emphasizing the necessity for regular updates and vigilance by system administrators to mitigate exposed attack surfaces.
