CVE-2026-67624: SQL Server Information Disclosure Vulnerability

CVE-2026-67624 Overview

CVE-2026-67624 is an out-of-bounds read vulnerability in Microsoft SQL Server. An authorized attacker can exploit the flaw over a network to disclose sensitive information from process memory. The issue is classified under [CWE-125] (Out-of-bounds Read).

The vulnerability requires low-privilege authenticated access and no user interaction. Successful exploitation compromises confidentiality but does not affect data integrity or system availability. Microsoft has published a security advisory in the Microsoft CVE-2026-67624 Update Guide.

Critical Impact
An authenticated attacker with network access to a vulnerable SQL Server instance can read memory outside intended buffer boundaries, potentially exposing sensitive data such as query fragments, credentials, or other in-memory artifacts.

Affected Products

Microsoft SQL Server (specific affected versions listed in the Microsoft Update Guide)
Refer to the Microsoft CVE-2026-67624 Update Guide for the authoritative product and build list
Not Available

Discovery Timeline

2026-09-08 - CVE-2026-67624 published to NVD
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-67624

Vulnerability Analysis

The vulnerability is an out-of-bounds read [CWE-125] within Microsoft SQL Server. Certain query or protocol handling paths read beyond the bounds of an allocated buffer. The returned data can include adjacent memory contents belonging to the SQL Server process.

Because the impact is limited to confidentiality, the flaw does not permit modification of data or denial of service. However, disclosed memory may contain query results, authentication tokens, or session data that support follow-on attacks. The attacker must already possess valid credentials on the target instance.

Root Cause

The root cause is missing or insufficient bounds validation when SQL Server processes attacker-controlled input during query execution or protocol parsing. When the server accesses memory using an untrusted length or offset, it reads past the end of the intended buffer. Microsoft has not published detailed technical internals for the affected code path.

Attack Vector

Exploitation occurs over the network against a reachable SQL Server endpoint, typically TCP port 1433. The attacker authenticates with valid credentials, then issues a crafted query, stored procedure call, or protocol message that triggers the out-of-bounds read. The server returns memory contents to the attacker through result sets or error responses.

No verified proof-of-concept code is currently available. Refer to the Microsoft CVE-2026-67624 Update Guide for vendor-supplied technical details.

Detection Methods for CVE-2026-67624

Indicators of Compromise

Unusual query patterns from low-privilege accounts, particularly repeated calls to the same function with varying length or offset parameters
Unexpected large or malformed result sets returned to client sessions from otherwise routine queries
Elevated volume of SQL Server error log entries referencing access violations, memory faults, or query aborts
Authentication events from atypical source hosts followed by anomalous T-SQL activity

Detection Strategies

Enable SQL Server Audit to capture all statements executed by non-administrative logins and forward events to a centralized log platform
Correlate authentication events with query telemetry to identify accounts issuing malformed or repetitive probing queries
Baseline normal query patterns per application account and alert on statistical deviations in query size, frequency, or result volume

Monitoring Recommendations

Monitor SQL Server error logs and Windows Application event logs for access violations and stack dumps originating in sqlservr.exe
Track outbound data volumes from database servers to detect bulk exfiltration following authenticated access
Review network access control lists to confirm SQL Server endpoints are not exposed to untrusted networks

How to Mitigate CVE-2026-67624

Immediate Actions Required

Apply the security update referenced in the Microsoft CVE-2026-67624 Update Guide to all affected SQL Server instances
Inventory SQL Server deployments and identify instances accessible from untrusted networks or shared application tiers
Rotate credentials for any low-privilege database accounts that may have been misused, and review recent audit logs for anomalous activity
Enforce the principle of least privilege on all database logins to reduce the pool of accounts capable of exploiting the flaw

Patch Information

Microsoft has issued a security update for CVE-2026-67624. Consult the Microsoft CVE-2026-67624 Update Guide for the specific cumulative update or GDR package that corresponds to your SQL Server version and build. Apply the update through Microsoft Update, WSUS, or manual installation following vendor guidance.

Workarounds

Restrict network access to SQL Server endpoints using firewalls, network security groups, or IPsec so only trusted application hosts can connect
Remove unnecessary logins and revoke PUBLIC permissions on sensitive objects to reduce the attacker's available surface
Require strong authentication and enforce credential rotation for all database accounts, particularly service and application accounts

bash

# Configuration example: restrict inbound access to SQL Server (TCP 1433)
# using Windows Firewall to a specific trusted application subnet
New-NetFirewallRule -DisplayName "SQL Server - Trusted App Tier Only" \
  -Direction Inbound \
  -Protocol TCP \
  -LocalPort 1433 \
  -RemoteAddress 10.20.30.0/24 \
  -Action Allow

# Block all other inbound traffic to 1433
New-NetFirewallRule -DisplayName "SQL Server - Block Other" \
  -Direction Inbound \
  -Protocol TCP \
  -LocalPort 1433 \
  -Action Block