CVE-2023-21529

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

Overview

State: PUBLISHED
Assigner (CNA): microsoft
CVSS severity: HIGH
CVSS score: 8.8 / 10
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Effective score: 8.8 / 10 HIGH source: CNA overview
MSRC score: 8.8 / 10 HIGH MS rating: Important · Remote Code Execution
CWE(s): CWE-502
Reserved: 2022-12-01
Published: 2023-02-14 08:00 UTC
Last updated: 2023-02-14 08:00 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2023/21xxx/CVE-2023-21529.json
Linked Threat: CVE-2023-21529 — Microsoft Exchange Server: Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability

CISA Known Exploited Vulnerabilities CISA KEV

CISA has confirmed in-the-wild exploitation of this CVE. Federal agencies must remediate by the due date below; private orgs should treat it as priority-1.

Vulnerability name: Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
Vendor / project: Microsoft
Product: Exchange Server
Date added to KEV: 2026-04-13
Remediation due: 2026-04-27
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Ransomware campaign use: Known
CISA notes: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529 ; https://nvd.nist.gov/vuln/detail/CVE-2023-21529
CISA listing: www.cisa.gov/known-exploited-vulnerabilities-catalog

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2023-02-14 20:15:11 UTC
NVD last modified: 2026-04-14 14:44:35 UTC
NVD CVSS v3.1: 8.8 / 10 HIGH source: secure@microsoft.com
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Exploitability subscore: 2.8 / 10
Impact subscore: 5.9 / 10
EPSS score: 0.3233 (probability of exploitation in next 30 days)
EPSS percentile: 96.91% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2023-25697
Assigner: microsoft
Published: Feb 14, 2023, 7:33:00 PM
Updated: Apr 14, 2026, 3:55:24 AM
EUVD base score (CVSS 3.1): 8.8 / 10
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
EUVD-reported EPSS: 27.5500
Vendors: Microsoft
Products: Microsoft Exchange Server 2013 Cumulative Update 23 (15.00.0 <15.00.1497.047)

Microsoft Exchange Server 2016 Cumulative Update 23 (15.01.0 <15.01.2507.021)

Microsoft Exchange Server 2019 Cumulative Update 11 (15.02.0 <15.02.0986.041)

Microsoft Exchange Server 2019 Cumulative Update 12 (15.02.0 <15.02.1118.025)
Aliases: GHSA-hjxr-gv9h-rjxc

ENISA description: Microsoft Exchange Server Remote Code Execution Vulnerability

EUVD references (1)

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529

Microsoft Security Response Center MSRC

Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-07-10 04:31 UTC (source: CVRF).

MS severity: Important
Impact: Remote Code Execution
MS CVSS base score: 8.8 / 10 (temporal 7.7)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Exploit assessment: Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation More Likely;DOS:N/A
Release: 2023-Feb

Microsoft remediations / KB articles (5)

5023038 — Vendor Fix / Security Update (fixed build 15.02.1118.025)
5023038 — Update
5023038 — Vendor Fix / Security Update (fixed build 15.02.0986.041)
5023038 — Vendor Fix / Security Update (fixed build 15.00.1497.047)
5023038 — Vendor Fix / Security Update (fixed build 15.01.2507.021)

Microsoft FAQ (2)

According to the CVSS metric, the attack vector is network (AV:N) and the user interaction is none (UI:N). What is the target used in the context of the remote code execution?

The attacker for this vulnerability could target the server accounts in an arbitrary or remote code execution. As an authenticated user, the attacker could attempt to trigger malicious code in the context of the server's account through a network call.

According to the CVSS metric, privileges required is low (PR:L). Does the attacker need to be in an authenticated role on the Exchange Server?

Yes, the attacker must be authenticated.

Affected products (4)

Vendor	Product	Versions	Platforms
Microsoft	Microsoft Exchange Server 2019 Cumulative Update 12	`15.02.0` (affected)	x64-based Systems
Microsoft	Microsoft Exchange Server 2019 Cumulative Update 11	`15.02.0` (affected)	x64-based Systems
Microsoft	Microsoft Exchange Server 2013 Cumulative Update 23	`15.00.0` (affected)	x64-based Systems
Microsoft	Microsoft Exchange Server 2016 Cumulative Update 23	`15.01.0` (affected)	x64-based Systems

Affected products — CPE 2.3 (4) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_23:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_11:*:*:*:*:*:*
cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_12:*:*:*:*:*:*

Vendor references (1)

References embedded in the original CVE record by the assigning CNA.

Microsoft Exchange Server Remote Code Execution Vulnerability vendor-advisory

MITRE references (1) cveawg.mitre.org

Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.

Microsoft Exchange Server Remote Code Execution Vulnerability vendor-advisory

Web references (9)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

5023038 msrc
5023038 msrc
5023038 msrc
5023038 msrc
https://support.microsoft.com/en-us/help/5023038 rapid7:support.microsoft.com
https://www.cve.org/CVERecord?id=CVE-2023-21529 rapid7:www.cve.org
https://attackerkb.com/topics/CVE-2023-21529 rapid7:attackerkb.com
https://support.microsoft.com/help/5023038 rapid7:support.microsoft.com
http://cwe.mitre.org/data/definitions/502.html rapid7:cwe.mitre.org

NVD-tagged references (4)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529 secure@microsoft.com PatchVendor Advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529 af854a3a-2127-422b-91ae-364da2661108 PatchVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-21529 134c704f-9b21-4f2e-91b3-4a467353bcc0 US Government Resource
https://www.microsoft.com/en-us/security/blog/2026/04/06/storm-1175-focuses-gaze-on-vulnerable-web-facing-assets-in-high-tempo-medusa-ransomware-operations/ 134c704f-9b21-4f2e-91b3-4a467353bcc0 Technical Description

Indicators (2)

IOCs linked to the auto-promoted Threat row.

Type	Value	VirusTotal	Attached
cve	`CVE-2023-21529`	no local data	2026-05-14 02:58 UTC
cwe	`CWE-502`	no local data	2026-05-14 02:58 UTC

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

Rapid7 — Solution

rapid7

msft-kb5023038-0114c451-a5b6-4e1a-8da5-f20a2bc43f10

2026-05-28 22:57 UTC
Security Update Guide - Microsoft

web:portal.msrc.microsoft.com

The Security Update Guide provides information on the latest Microsoft security updates, helping users understand and address potential vulnerabilities effectively.

2026-05-14 09:18 UTC
KB4073119: Windows client guidance for IT Pros to protect against ...

web:support.microsoft.com

Provides Windows client guidance for IT Pros to protect against speculative execution side-channel vulnerabilities.

2026-05-14 09:18 UTC
Landing Page | ServiceNow Common Vulnerabilities & Exposures (CVE ...

web:support.servicenow.com

Overview The advisories below document publicly disclosed Common Vulnerabilities and Exposures ( CVEs ) in the Now Platform by ServiceNow. Because ServiceNow uses various methods to communicate vulnerability information, patches, and other fixes, customers should review family, security patch , and hotfix release notes, which are available at https://docs.servicenow.com, for a complete list of ...

2026-05-14 09:18 UTC
Microsoft March 2026 Patch Tuesday fixes 2 zero-days, 79 flaws

web:www.bleepingcomputer.com

Today is Microsoft's March 2026 Patch Tuesday with security updates for 79 flaws, including 2 publicly disclosed zero-day vulnerabilities.

2026-05-14 09:18 UTC
Patch Tuesday May 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-05-14 09:18 UTC
Dangerous Fake Microsoft Windows Update Confirmed—Do Not Download

web:www.forbes.com

As security researchers warn about a dangerous Microsoft Windows update that isn't legitimate, users must pay close attention to what they are actually downloading.

2026-05-14 09:18 UTC
Oracle Critical Patch Update Advisory - April 2026

web:www.oracle.com

This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

2026-05-14 09:18 UTC
Microsoft Issues Massive Windows Patch for 160+ Bugs, Including Two ...

web:www.techrepublic.com

Microsoft's April 2026 Patch Tuesday fixes 165 vulnerabilities, including two zero-days, in one of the company's largest monthly security updates.

2026-05-14 09:18 UTC
CISA Required Action

CISA KEV

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Due date: 2026-04-27 Known ransomware campaign use: Known

2026-05-14 01:13 UTC

AI Forensic Analysis

Only Available for Registered Users. Sign in to view.

Raw JSON

The full cvelistV5 record. Download as CVE-2023-21529.json.

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