Executive brief
Microsoft Exchange Server, the platform used by organizations for email and calendaring, contains a vulnerability that allows an unauthorized person to send deceptive communications. An attacker could use this to impersonate legitimate senders or services, potentially leading to successful phishing attempts or the distribution of misinformation within the corporate network. This issue affects the integrity of email communications but does not directly grant access to private data or cause system downtime.
Technical details
A spoofing vulnerability exists in Microsoft Exchange Server due to improper validation of syntactic correctness of input (CWE-1286). An unauthenticated attacker can exploit this vulnerability over the network by sending specially crafted requests to an affected server. Successful exploitation allows the attacker to perform spoofing attacks, potentially bypassing filters or misrepresenting the origin of communications. The vulnerability affects multiple versions of Exchange Server 2016 and 2019. Microsoft has released security updates to address this issue; administrators should refer to the MSRC Update Guide for specific patch details.
Affected products
- Microsoft Exchange Server 2016 Cumulative Update 1 through 23
- Microsoft Exchange Server 2019 Cumulative Update 1 through 14
Timeline
- 2025-08-12: advisory: Initial publication by Microsoft and NVD