Domain privilege escalation via unsafe schema class
Published Jul 14, 2021 · Updated Aug 10, 2026
Privilege escalation in Microsoft Exchange Server 2013 CU23, 2016 CU21, and 2019 CU10 allows low-privileged domain users to gain higher privileges. The Exchange-installed Active Directory msExchStorageGroup schema class permits creation beneath computer objects, exposing an unsafe object-creation path. An authenticated user with adjacent network access can abuse the permissive schema relationship to create directory objects and compromise domain security.
Summary
What happened
Privilege escalation in Microsoft Exchange Server 2013 CU23, 2016 CU21, and 2019 CU10 allows low-privileged domain users to gain higher privileges. The Exchange-installed Active Directory msExchStorageGroup schema class permits creation beneath computer objects, exposing an unsafe object-creation path. An authenticated user with adjacent network access can abuse the permissive schema relationship to create directory objects and compromise domain security.
The record
- CVE
- CVE-2021-34470
- Published
- Jul 14, 2021
- Updated
- Aug 10, 2026
- Vendor
- Microsoft
- Product
- Microsoft Exchange Server 2016 Cumulative Update 21
- Classifications
- T1068
- Attack vector
- adjacent
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 14, 2021CVE publishedPublication date reported by the CVE source.
- Aug 10, 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.
- Affected versionversion=15.01.0 <15.01.2308.008
What conditions does exploitation require?
What is affected?
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.
Weakness, pattern, technique
Public exploit references
- Microsoft Exchange AD Schema Misconfiguration Privilege Escalationproof of concept · unverified
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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