CVE-2021-1636Network attack vector

Authenticated code execution via enabled extended event

Published Jan 12, 2021 · Updated Oct 8, 2024

Code execution in Microsoft SQL Server 2012 through 2019 allows remote authenticated users to run code in the server process over the network. The SQL Server Engine processes network-supplied data unsafely when an unnamed extended event is enabled; Microsoft has not disclosed the event or faulty routine. A valid low-privilege database login and that event state are required, and successful exploitation gains the SQL Server process's privileges.

CVSS severity8.8
High
EPSS probability6.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code execution in Microsoft SQL Server 2012 through 2019 allows remote authenticated users to run code in the server process over the network. The SQL Server Engine processes network-supplied data unsafely when an unnamed extended event is enabled; Microsoft has not disclosed the event or faulty routine. A valid low-privilege database login and that event state are required, and successful exploitation gains the SQL Server process's privileges.

The record

CVE
CVE-2021-1636
Published
Jan 12, 2021
Updated
Oct 8, 2024
Vendor
Microsoft
Product
Microsoft SQL Server 2016
Classifications
CWE-89, T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 12, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 8, 2024Record 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 <publication

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft SQL Server 2016version=13.0.0 <publication
Microsoft · Microsoft SQL Server 2012version=11.0.0 <publication
Microsoft · Microsoft SQL Server 2019version=15.0.0 <publication; version=16.0.0 <publication
Microsoft · Microsoft SQL Server 2017version=14.0.0 <publication
Microsoft · Microsoft SQL Server 2014version=12.0.0 <publication

Published CVSS scores

8.8NISTCVSS:3.1/AV:N/AC:L/PR:L/UI:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-89Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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