CVE-2023-21529 - PatchNow

📋 Vulnerability Details

Data Source: CIRCL

Confidence: HIGH

Exploitation Method: DIRECT_NETWORK

CVE Published: 2023-02-14

Added to CISA KEV: 2026-04-13 1154 DAYS BETWEEN CVE AND KEV

🎯 Recommendations:

CRITICAL: Check for indicators of compromise - this vulnerability is in CISA KEV indicating active exploitation in the wild. Review logs, check for unauthorized access, verify system integrity
Apply Microsoft security updates immediately for affected Exchange Server versions
Monitor Exchange server logs for suspicious authentication attempts and unusual process execution
Consider temporarily restricting external access to Exchange services until patching is complete
Implement network segmentation to limit potential lateral movement if compromise occurs

🔍 Web Intelligence (Kagi · 2026-06-04)

CVE-2023-21529 is a critical Remote Code Execution (RCE) vulnerability affecting Microsoft Exchange Server ^[5] ^[2]. It was disclosed as part of Microsoft's February 2023 Patch Tuesday updates ^[6].

Key Details of CVE-2023-21529

Feature	Details
Vulnerability Type	Remote Code Execution (RCE) ^[5]
Affected Products	Microsoft Exchange Server 2013, 2016, and 2019 ^[2]
Exploitation Requirements	Requires authentication ^[3]
Impact	Allows attackers to execute arbitrary code, install backdoors, or steal sensitive data ^[2]
Status	Included in CISA's Known Exploited Vulnerabilities (KEV) Catalog ^[1]

Exploitation and Threat Landscape

Authentication Requirement: Unlike some other high-profile Exchange vulnerabilities (such as those involving SSRF to bypass authentication), CVE-2023-21529 requires the attacker to be authenticated to the target system to achieve RCE ^[3].
Active Exploitation: The vulnerability is listed in the CISA Known Exploited Vulnerabilities (KEV) Catalog, indicating that it has been actively exploited in the wild ^[1].
Impact: Successful exploitation grants an attacker the ability to run code with the privileges of the Exchange service, which can lead to full system compromise, lateral movement within the network, and data exfiltration ^[2].

Mitigation and Patch Status

Patching: Microsoft released security updates in February 2023 to address this vulnerability. Organizations are strongly advised to apply the latest Cumulative Updates (CU) and Security Updates (SU) for their specific version of Exchange Server to mitigate the risk ^[4].
Guidance: Because this is a known exploited vulnerability, CISA mandates that federal agencies and other organizations prioritize patching this flaw to prevent unauthorized access ^[1].

Sources

NVD - CVE-2023-21529
An official website of the United States government NVD MENU ... This CVE is in CISA's Known Exploited Vulnerabilities Catalog. Reference CISA's BOD 22-01 and Known Exploited Vulnerabilities Catalog for further guidance and ... CVE-2023-21529 Detail. Modified. This vulnerability has been modified si…
CVE-2023-21529 - How Hackers Remotely Exploit Microsoft Exchange Server ...
Below, we’ll break down this vulnerability in plain English, show how exploitation works, offer sample code, and link original references so you can dig deeper and stay protected. What is CVE-2023-21529? CVE-2023-21529 lives in Microsoft Exchange Server, a popular software used by businesses for ema…
GreyNoise Analysis Of A Quartet of Exchange Remote Code ...
CVE-2023-21529, CVE-2023-21706, and CVE-2023-21707 have similarities to CVE-2022-41082 due to them all requiring authentication to achieve remote code ... CVE-2023-21529, CVE-2023-21706, and CVE-2023-21707 have similarities to CVE-2022-41082 due to them all requiring authentication to achieve remote…
CVE-2023-21529: Microsoft Exchange Server RCE Vulnerability
Learn about CVE-2023-21529, a critical Remote Code Execution flaw in Microsoft Exchange Server impacting versions including 2019 and 2016. Find mitigation steps and updates.CVE-2023-21529 is a Remote Code Execution vulnerability present in Microsoft Exchange Server, which can be exploited by threat…
CVE-2023-21529: Microsoft Exchange Server RCE Vulnerability
CVE-2023-21529 is a remote code execution vulnerability in Microsoft Exchange Server that enables attackers to execute arbitrary code remotely. ... CVE-2023-21529 is a remote code execution vulnerability in Microsoft Exchange Server that enables attackers to execute arbitrary code remotely. This art…
Top Trending CVEs of February 2023 - NopSec
In this month's trending CVEs we have a number of patches released by Microsoft to address critical vulnerabilities identified in Exchange and Windows ...