Microsoft SQL Server 0-Day Vulnerability Exposes Sensitive Data Over Network

A critical information disclosure vulnerability in Microsoft SQL Server, designated as CVE-2025-49719, allows unauthorized attackers to access sensitive data over network connections. 

This vulnerability stems from improper input validation within SQL Server’s processing mechanisms, enabling attackers to disclose uninitialized memory contents without requiring authentication or user interaction. 

Key Takeaways
1. Critical SQL Server bug (CVE-2025-49719) exposes sensitive data due to improper input validation.
2. Exploitable over the network, affecting SQL Server 2016–2022 with no authentication needed.
3. Microsoft has released essential security patches immediate updates are strongly advised.
4. Attackers may access uninitialized memory, leaking confidential database information.

The vulnerability affects multiple SQL Server versions from 2016 through 2022, with security updates released on July 8, 2025, to address this significant security concern.

SQL Server Information Disclosure Vulnerability (CVE-2025-49719) 

The CVE-2025-49719 vulnerability is classified under CWE-20: Improper Input Validation, representing a fundamental flaw in how SQL Server processes incoming network requests. 

The vulnerability carries a CVSS 3.1 base score of 7.5 with a temporal score of 6.5, categorizing it as “Important” severity. 

The technical weakness allows attackers to exploit insufficient input validation routines, potentially accessing uninitialized memory regions that may contain sensitive database information, connection strings, or other confidential data structures.

The vulnerability’s attack vector characteristics make it particularly concerning for enterprise environments. 

The CVSS vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N indicates network-based attacks with low complexity, requiring no privileges or user interaction. 

This configuration enables remote attackers to potentially extract sensitive information from SQL Server instances exposed to network access, making it a prime target for automated exploitation tools and reconnaissance activities.

The exploitation mechanism leverages network-based attack vectors that require no authentication credentials or user interaction, significantly lowering the barrier for successful attacks. 

Attackers can craft malicious network packets targeting SQL Server’s input validation routines, potentially triggering the disclosure of uninitialized memory contents. 

The vulnerability’s network accessibility means that any SQL Server instance reachable over TCP/IP connections could be vulnerable to information disclosure attacks.

The exploitability assessment indicates that while the vulnerability has been publicly disclosed, active exploitation remains “Less Likely” according to Microsoft’s analysis. 

However, the combination of network accessibility and no authentication requirements creates a substantial attack surface for threat actors. 

Organizations running SQL Server in cloud environments, particularly Windows Azure IaaS deployments, face additional exposure risks due to the broader network attack surface inherent in cloud infrastructure.

Remediation 

Microsoft has released comprehensive security updates addressing CVE-2025-49719 across all supported SQL Server versions. 

The remediation strategy involves applying version-specific updates, including both General Distribution Release (GDR) and Cumulative Update (CU) packages. 

Critical updates include KB 5058721 for SQL Server 2022 CU19+GDR (version 16.0.4200.1), KB 5058722 for SQL Server 2019 CU32+GDR (version 15.0.4435.7), and KB 5058714 for SQL Server 2017 CU31+GDR (version 14.0.3495.9).

Organizations must prioritize immediate patch deployment, particularly for internet-facing SQL Server instances. 

Database administrators should implement network segmentation and access controls as additional protective measures while coordinating update deployment across enterprise environments.

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