Summary
Impact: Elevation of Privilege. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
How could an attacker exploit this vulnerability?
An authenticated attacker with low privileges could poison a shared cache used by the Exchange Control Panel, causing a malicious mail add-in to be installed in the context of another user's mailbox. Successful exploitation could allow the attacker to gain elevated privileges in the affected mailbox context. User interaction is not required.
According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
Successful exploitation of this vulnerability requires an attacker to have a deep understanding of the system. Successful exploitation is not guaranteed and depends on a combination of factors that might include the environment, system configuration, and the presence of additional security measures.
Security updates
15.02.1748.055 — https://support.microsoft.com/help/5128896
15.02.2562.056 — https://support.microsoft.com/help/5128895
15.02.1544.050 — https://support.microsoft.com/help/5128897
15.01.2507.077 — https://support.microsoft.com/help/5128898
Vulnerabilities 1
-
High 7.5
Microsoft Exchange Server Elevation of Privilege Vulnerability
Improper verification of cryptographic signature in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
Revision history
-
#1
Information published.
References
-
CVE-2026-87696 Microsoft Exchange Server Elevation of Privilege Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-87696
-
Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
-
Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
-
Common Vulnerability Scoring System
https://www.first.org/cvss