CVE-2023-36756

Authenticated SYSTEM code execution via unsafe deserialization

Published Sep 12, 2023 · Updated Oct 30, 2025

Deserialization in Microsoft Exchange Server allows remote authenticated users to execute arbitrary code as SYSTEM through crafted data. The ApprovedApplicationCollection class accepts user-controlled serialized content without adequate validation and deserializes it. Exploitation requires authenticated adjacent-network access and grants code execution in the Exchange service's SYSTEM context.

CVSS severity8.0
High
EPSS probability49.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deserialization in Microsoft Exchange Server allows remote authenticated users to execute arbitrary code as SYSTEM through crafted data. The ApprovedApplicationCollection class accepts user-controlled serialized content without adequate validation and deserializes it. Exploitation requires authenticated adjacent-network access and grants code execution in the Exchange service's SYSTEM context.

The record

CVE
CVE-2023-36756
Published
Sep 12, 2023
Updated
Oct 30, 2025
Vendor
Microsoft
Product
Microsoft Exchange Server 2019 Cumulative Update 12
Classifications
CWE-502, T1190
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 12, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 30, 2025Record 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=15.02.0 <15.02.1118.037

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft Exchange Server 2019 Cumulative Update 12version=15.02.0 <15.02.1118.037
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 13version=15.02.0 <15.02.1258.025
Microsoft · Microsoft Exchange Server 2016 Cumulative Update 23version=15.01.0 <15.01.2507.032

Published CVSS scores

8.8Trend Micro Zero Day InitiativeCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.0Microsoft CorporationCVSS: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

CWE-502Deserialization of Untrusted Data
T1190Exploit Public-Facing Application

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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