CVE-2023-21529
Published: April 11, 2026
Official Description
Microsoft Exchange Server Remote Code Execution Vulnerability
Technical Analysis
CVE-2023-21529 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2023-21529 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Affected Vendors & Products
Exploit & PoC Resources
News & Research Mentioning CVE-2023-21529
CISA has added seven new vulnerabilities to its Known Exploited Vulnerabilities (KEV) Catalog, based on evidence of active exploitation. CVE-2012-1854 Microsoft Visual Basic for Applications Insecure Library Loading Vulnerability CVE-2020-9715 Adobe Acrobat Use-After-Free Vulnerability CVE-2023-21529 Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability CVE-2023-36424 Microsoft Windows Out-of-Bounds Read Vulnerability CVE-2025-60710 Microsoft Windows Link Following Vulnerability CVE-2026-21643 Fortinet SQL Injection Vulnerability CVE-2026-34621 Adobe Acrobat and Reader Prototype Pollution Vulnerability These types of vulnerabilities are frequent attack vectors for malicious cyber actors and pose significant risks to the federal en [xlite_meta score:63 src:CISA Alerts xlite_fp:60f6f1bcbc9a5044d679f054f7e8c0299964fe8ffd48c04cf355066842ed73c8]
Quick Facts
Known Threat Actors
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2023-21529 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1