Microsoft Exchange Server Elevation of Privilege Vulnerability

Source data

Overview

Improper verification of cryptographic signature in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.

Impact & technical details

Elevation of Privilege

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.

CVSS base score

7.5 / 10

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Highest base score supplied by MSRC for this record; the vector belongs to that score. Ratings can vary by product. Microsoft Important is displayed as High; Moderate is displayed as Medium.

Affected products

• Microsoft Exchange Server 2016 Cumulative Update 23
• Microsoft Exchange Server 2019 Cumulative Update 14
• Microsoft Exchange Server 2019 Cumulative Update 15
• Microsoft Exchange Server Subscription Edition RTM

Source guidance

Remediation

The source provides update references without a separate remediation summary. Review the applicable update links below.

At least one Microsoft vendor-fix reference is available. Check each affected product for its applicable update, prerequisites, and supported version.

Authoritative sources & updates

Findings and update information come from the linked publishers. GTP compiles the public record and provides the recommendation above. CVSS ratings shown here come from Microsoft. NVD references provide additional public context.

• Microsoft Security Response Center (opens in a new tab)
• Microsoft remediation guidance (opens in a new tab)
• Microsoft security update · 5128895 (opens in a new tab)
• Microsoft remediation guidance (opens in a new tab)
• Microsoft remediation guidance (opens in a new tab)
• Microsoft remediation guidance (opens in a new tab)