CVE-2023-36439

Authenticated code execution via untrusted deserialization

Published Nov 14, 2023 · Updated Oct 8, 2025

Deserialization in Microsoft Exchange Server 2016 CU23 and 2019 CU12 and CU13 allows remote authenticated users to execute arbitrary code. Microsoft maps the flaw to CWE-502 but has not published the deserialization entry point, payload format, or unsafe object-processing operation. Exploitation requires low-privileged access from an adjacent network, and successful execution can fully compromise the server.

CVSS severity8.0
High
EPSS probability4.92%
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 2016 CU23 and 2019 CU12 and CU13 allows remote authenticated users to execute arbitrary code. Microsoft maps the flaw to CWE-502 but has not published the deserialization entry point, payload format, or unsafe object-processing operation. Exploitation requires low-privileged access from an adjacent network, and successful execution can fully compromise the server.

The record

CVE
CVE-2023-36439
Published
Nov 14, 2023
Updated
Oct 8, 2025
Vendor
Microsoft
Product
Microsoft Exchange Server 2019 Cumulative Update 12
Classifications
CWE-502
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 14, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 8, 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 <15.02.1118.040

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

Microsoft · Microsoft Exchange Server 2019 Cumulative Update 12version=15.02.0 <15.02.1118.040
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 13version=15.02.0 <15.02.1258.028
Microsoft · Microsoft Exchange Server 2016 Cumulative Update 23version=15.01.0 <15.01.2507.035

Published CVSS scores

8.0MicrosoftCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.0MicrosoftCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

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

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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