CVE-2026-47297: SQL Server RCE Vulnerability

CVE-2026-47297 Overview

CVE-2026-47297 is a deserialization of untrusted data vulnerability in Microsoft SQL Server. An unauthorized attacker can execute code over a network by sending crafted serialized data to a vulnerable SQL Server instance. The flaw is tracked under CWE-502, Deserialization of Untrusted Data, and requires no authentication or user interaction.

Microsoft published the advisory on September 8, 2026, and the entry was last modified on September 9, 2026. Refer to the Microsoft CVE-2026-47297 Advisory for vendor-supplied fix guidance.

Critical Impact
Successful exploitation grants remote code execution on the SQL Server host with full loss of confidentiality, integrity, and availability.

Affected Products

Microsoft SQL Server (specific supported versions listed in the Microsoft advisory)
Any application stack depending on affected SQL Server instances
Managed environments where SQL Server is reachable over untrusted networks

Discovery Timeline

2026-09-08 - CVE-2026-47297 published to NVD
2026-09-09 - Last updated in NVD database

Technical Details for CVE-2026-47297

Vulnerability Analysis

The vulnerability resides in SQL Server code paths that deserialize attacker-supplied data without adequate type or integrity validation. When a vulnerable component reconstructs objects from a serialized stream, a crafted payload can trigger unintended object graphs during instantiation. This behavior allows an attacker to influence method invocation during the deserialization process.

An unauthenticated adversary reaching the SQL Server service over the network can submit malicious serialized content and coerce the server into executing attacker-controlled code. The EPSS probability is approximately 0.84%, reflecting current predicted exploitation likelihood rather than confirmed in-the-wild activity.

Refer to the Microsoft CVE-2026-47297 Advisory for authoritative component and version details.

Root Cause

The root cause is unsafe handling of serialized objects, classified under [CWE-502]. SQL Server accepts serialized input from network-reachable interfaces and reconstructs objects without enforcing a strict allow-list of expected types. This design flaw enables gadget-chain style abuse during object rehydration.

Attack Vector

The attack vector is network-based and requires no privileges or user interaction. An attacker sends a specially crafted serialized payload to a listening SQL Server endpoint. Successful exploitation results in arbitrary code execution in the security context of the SQL Server process.

No public proof-of-concept, exploit code, or CISA KEV listing exists for this CVE at the time of publication. Consult the vendor advisory for exploit prerequisites and any conditions that increase attack complexity.

Detection Methods for CVE-2026-47297

Indicators of Compromise

Unexpected child processes spawned by sqlservr.exe, particularly command shells, scripting hosts, or rundll32.exe.
Anomalous outbound network connections from SQL Server hosts to unknown or non-corporate destinations.
New or modified scheduled tasks, services, or persistence artifacts on database servers following anomalous inbound sessions.

Detection Strategies

Monitor SQL Server hosts for process lineage anomalies where sqlservr.exe invokes interpreters such as powershell.exe, cmd.exe, or wscript.exe.
Alert on inbound network traffic to SQL Server ports from segments that historically do not communicate with database tiers.
Correlate SQL Server error logs and Windows event logs for exception patterns tied to deserialization failures or unexpected assembly loads.

Monitoring Recommendations

Enable SQL Server audit for login events, extended stored procedure execution, and CLR assembly loading.
Ingest Windows Security, Sysmon, and SQL audit logs into a centralized analytics platform for cross-source correlation.
Baseline normal SQL client applications and flag connections originating from new binaries or service accounts.

How to Mitigate CVE-2026-47297

Immediate Actions Required

Apply the Microsoft security update referenced in the Microsoft CVE-2026-47297 Advisory to all affected SQL Server instances.
Inventory SQL Server hosts exposed to untrusted networks and prioritize patching for internet-reachable or DMZ deployments.
Rotate service account credentials and review recent authentication and query activity on database servers.

Patch Information

Microsoft has released updates addressing the deserialization flaw. Administrators should consult the vendor advisory for the exact KB numbers, cumulative updates, and supported SQL Server versions requiring the fix. Validate patch deployment status through configuration management tooling and confirm SQL Server build numbers post-installation.

Workarounds

Restrict network exposure of SQL Server by binding services to internal interfaces and enforcing firewall rules that permit only trusted application tiers.
Require TLS and strong authentication on all SQL Server endpoints to reduce anonymous access surface.
Segment database servers into dedicated network zones with strict east-west traffic controls until patches are applied.

bash

# Configuration example: restrict SQL Server inbound access with Windows Firewall
New-NetFirewallRule -DisplayName "Restrict SQL Server 1433" \
  -Direction Inbound \
  -Protocol TCP \
  -LocalPort 1433 \
  -RemoteAddress 10.10.20.0/24 \
  -Action Allow

New-NetFirewallRule -DisplayName "Block SQL Server 1433 Default" \
  -Direction Inbound \
  -Protocol TCP \
  -LocalPort 1433 \
  -Action Block