CVE-2023-21718

Code execution via incorrect TDS image decoding

Published Feb 14, 2023 · Updated Aug 19, 2026

Integer underflow in Microsoft ODBC Driver for SQL Server allows attackers to execute code when a user connects to a malicious database. An improper TDS version check makes the client decode image data types incorrectly, causing memory corruption in the ODBC driver. Exploitation requires user-initiated communication with a server using a down-level TDS version and runs code in the connecting process.

CVSS severity7.8
High
EPSS probability0.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer underflow in Microsoft ODBC Driver for SQL Server allows attackers to execute code when a user connects to a malicious database. An improper TDS version check makes the client decode image data types incorrectly, causing memory corruption in the ODBC driver. Exploitation requires user-initiated communication with a server using a down-level TDS version and runs code in the connecting process.

The record

CVE
CVE-2023-21718
Published
Feb 14, 2023
Updated
Aug 19, 2026
Vendor
Microsoft
Product
Microsoft SQL Server 2016 Service Pack 3 Azure Connect Feature Pack
Classifications
CWE-191, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 14, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=13.0.0 <13.0.7024.30

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Microsoft · Microsoft SQL Server 2016 Service Pack 3 Azure Connect Feature Packversion=13.0.0 <13.0.7024.30
Microsoft · Microsoft SQL Server 2008version=10.0.0 <10.0.6814.4
Microsoft · Microsoft SQL Server 2012version=11.0.0 <11.0.7512.11
Microsoft · Microsoft SQL Server 2022version=16.0.0 <16.0.1050.5
Microsoft · Microsoft SQL Server 2019version=15.0.0 <15.0.2101.7; version=15.0.0 <15.0.4280.7
Microsoft · Microsoft SQL Server 2017version=14.0.0 <14.0.2047.8; version=14.0.0 <14.0.3460.9
Microsoft · Microsoft SQL Server 2008 R2version=10.0.0 <10.50.6785.2
Microsoft · Microsoft SQL Server 2014version=12.0.0 <12.0.6174.8; version=12.0.0 <12.0.6444.4
Microsoft · Microsoft SQL Server 2016 Service Pack 3version=13.0.0 <13.0.6430.49

Published CVSS scores

7.8MicrosoftCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-191Integer Underflow (Wrap or Wraparound)
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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