Unauthenticated Remote Attacks Possible in SQL Server – Patch Now!

A newly disclosed vulnerability in Microsoft SQL Server versions 2016 through 2022 allows unauthenticated attackers to extract sensitive memory contents over the network without user interaction. This flaw arises from improper input validation, exposing confidential database information such as connection strings and internal memory data. Although exploitation is currently assessed as “less likely,” the low complexity and remote attack vector make it a serious threat to enterprise and cloud-hosted environments.

Severity Level: High

Vulnerability Details

• CVE ID: CVE-2025-49719
• CWE: CWE-20 (Improper Input Validation)
• CVSS Score: 7.5
• Vulnerability Type: Information Disclosure

Root Cause

The vulnerability originates from improper input validation in the SQL Server network protocol parser. Specifically, the input data sent over TCP/IP is not adequately sanitized before processing. This allows attackers to leverage uninitialized memory reads, revealing fragments of internal memory that may contain:

• Database content
• Connection strings
• Configuration metadata
• Other sensitive artifacts

Exploitation Of The Vulnerability

An attacker can exploit the vulnerability by:

1. Sending crafted network packets to the SQL Server over exposed ports (typically TCP 1433).
2. These packets are designed to trigger input validation flaws.
3. The server responds by disclosing segments of uninitialized memory, which may contain confidential information.
4. No credentials or user interaction is required – making mass exploitation possible, especially for internet-exposed servers.

Exploitation Risk:
Although Microsoft labels the exploitation likelihood as “Less Likely” currently, the low complexity, no authentication, and remote reachability make this highly exploitable with automated tools if unpatched.

Affected Products

The following Microsoft SQL Server versions are vulnerable:

• Microsoft SQL Server 2016
• Microsoft SQL Server 2017
• Microsoft SQL Server 2019
• Microsoft SQL Server 2022

All supported versions with unpatched builds are affected.

Recommendations

1. Immediately apply the official Microsoft security updates for all affected SQL Server versions.
2. Restrict SQL Server access to trusted IP ranges using host firewalls or perimeter security tools.
3. Block direct internet access to SQL Server ports (default TCP 1433); use VPN or bastion hosts.
4. Disable unused SQL features and services to reduce attack surface.

Source:

• https://cybersecuritynews.com/microsoft-sql-server-0-day-vulnerability/
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-49719

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