CVE-2026-67369 Overview
CVE-2026-67369 is an out-of-bounds read vulnerability in Microsoft SQL Server. An authorized attacker with low privileges can exploit the flaw over a network to disclose sensitive information from server memory. The weakness is classified as [CWE-125] Out-of-bounds Read.
The attack requires no user interaction and has low complexity. Exploitation impacts confidentiality only, with no direct effect on data integrity or availability. Successful exploitation could leak memory contents that include cached query results, credentials, or other server state accessible to the SQL Server process.
Critical Impact
An authenticated attacker can read memory beyond intended buffer boundaries in SQL Server, exposing sensitive information across a network connection.
Affected Products
- Microsoft SQL Server (specific versions listed in the Microsoft Security Update Guide)
- Deployments exposing SQL Server endpoints to authenticated network users
- Environments where low-privilege database logins are broadly issued
Discovery Timeline
- 2026-09-08 - CVE-2026-67369 published to the National Vulnerability Database
- 2026-09-08 - Last updated in NVD database
Technical Details for CVE-2026-67369
Vulnerability Analysis
The vulnerability is an out-of-bounds read [CWE-125] within Microsoft SQL Server. The database engine reads memory outside the bounds of an allocated buffer during processing of attacker-influenced input. The read operation returns adjacent memory contents to the caller instead of raising a controlled error.
Because the flaw is triggered over the network by an authenticated session, any principal that can establish a SQL Server connection can attempt exploitation. The scope remains unchanged, and no privilege escalation or code execution is directly achievable through this defect.
The practical risk is disclosure of process memory. Depending on server workload, leaked bytes may include portions of query buffers, session tokens, cached credentials, or plan-cache contents belonging to other users.
Root Cause
Out-of-bounds reads of this class typically stem from missing or incorrect length validation before a memory copy or field parse. The affected code path trusts a size, offset, or terminator value derived from client-supplied data and reads past the end of the source buffer. Microsoft has not published low-level technical detail beyond the Microsoft Security Update Guide.
Attack Vector
The attacker connects to the SQL Server instance over the network using valid but low-privileged credentials. The attacker then issues crafted queries, RPC calls, or protocol messages that trigger the vulnerable parsing path. The server returns response data containing bytes read past the intended buffer boundary. Repeated invocations can be used to harvest memory content across sessions.
No synthetic exploit code is published for this advisory. Refer to the Microsoft Security Update Guide for vendor-provided technical detail as it becomes available.
Detection Methods for CVE-2026-67369
Indicators of Compromise
- Repeated malformed or anomalously structured T-SQL, RPC, or TDS requests from a single low-privileged login
- Unusual volume of query responses containing binary or non-UTF-8 payloads returned to a single client
- Authentication activity from service accounts issuing queries outside their normal application pattern
- Connections from unexpected hosts or subnets to SQL Server listener ports (default TCP 1433)
Detection Strategies
- Enable SQL Server Audit for FAILED_LOGIN_GROUP, SUCCESSFUL_LOGIN_GROUP, and batch-level events, then baseline query patterns per principal
- Deploy network monitoring on TDS traffic to flag oversized or malformed protocol data units
- Correlate SQL error log entries referencing access violations, dump files, or stack dump events with recent client activity
Monitoring Recommendations
- Forward SQL Server audit logs and Windows Application event logs to a centralized analytics pipeline
- Alert on new logins performing schema enumeration followed by high-frequency query bursts
- Track outbound data volume per authenticated database session to detect memory-scraping behavior
How to Mitigate CVE-2026-67369
Immediate Actions Required
- Apply the Microsoft security update for CVE-2026-67369 to all affected SQL Server instances
- Inventory all SQL Server deployments, including embedded and developer editions, to confirm patch coverage
- Rotate credentials for any low-privileged accounts suspected of unauthorized use during the exposure window
- Restrict inbound network access to SQL Server listeners to trusted application tiers only
Patch Information
Microsoft has published guidance and update packages through the Microsoft Security Update Guide for CVE-2026-67369. Administrators should identify the applicable cumulative update or GDR package for each installed SQL Server version and deploy through standard patch management channels.
Workarounds
- Enforce network segmentation so SQL Server endpoints are unreachable from user workstations and the public internet
- Require Windows Authentication and remove unused SQL logins to reduce the population of accounts able to reach the vulnerable code path
- Apply least-privilege database roles and revoke unnecessary CONNECT permissions on production instances
- Enable TLS for SQL Server connections to make anomalous protocol inspection at the network edge more reliable
# Example: enumerate SQL Server logins and disable unused low-privilege accounts
sqlcmd -S <server> -Q "SELECT name, is_disabled, type_desc FROM sys.server_principals WHERE type IN ('S','U','G');"
sqlcmd -S <server> -Q "ALTER LOGIN [unused_login] DISABLE;"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
