CVE-2021-33768

Adjacent authenticated elevation of privilege

Published Jul 14, 2021 · Updated Aug 10, 2026

Elevation of privilege in Microsoft Exchange Server 2016 and 2019 allows remote authenticated users to gain elevated rights. Microsoft has not published the affected component, vulnerable operation, or input path. Exploitation requires adjacent-network access and an existing low-privilege account; the exact elevated rights remain undisclosed.

CVSS severity8.0
High
EPSS probability1.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Elevation of privilege in Microsoft Exchange Server 2016 and 2019 allows remote authenticated users to gain elevated rights. Microsoft has not published the affected component, vulnerable operation, or input path. Exploitation requires adjacent-network access and an existing low-privilege account; the exact elevated rights remain undisclosed.

The record

CVE
CVE-2021-33768
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

  1. Jul 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=15.01.0 <15.01.2308.014

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft Exchange Server 2016 Cumulative Update 21version=15.01.0 <15.01.2308.014
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 10version=15.02.0 <15.02.0922.013
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 9version=15.02.0 <15.02.0858.015
Microsoft · Microsoft Exchange Server 2016 Cumulative Update 20version=15.01.0 <15.01.2242.012

Published CVSS scores

8.0Microsoft CorporationCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.0NIST NVDCVSS:3.1/AV:A/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1068Exploitation for Privilege Escalation

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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