CVE-2021-41349
Published: April 11, 2026
Official Description
Microsoft Exchange Server Spoofing Vulnerability
Risk Analysis
This is a spoofing vulnerability affecting Microsoft Exchange Server. While specific details of the flaw are not provided, spoofing vulnerabilities can allow attackers to impersonate legitimate users or systems, potentially leading to further attacks. Its inclusion in CISA's KEV catalog indicates confirmed exploitation in the wild, making it a critical vulnerability.
This vulnerability has been actively exploited in the wild and is listed in CISA's Known Exploited Vulnerabilities catalog. Attackers are leveraging this flaw to spoof identities within Microsoft Exchange Server environments.
Administrators of Microsoft Exchange Server should apply all available security updates and patches from Microsoft to address this spoofing vulnerability. Regularly review and enforce strong authentication policies.
Technical Analysis
CVE-2021-41349 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-2021-41349 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
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-41349 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