Microsoft Exchange Server Elevation of Privilege Vulnerability
Published September 8, 2026Updated September 8, 2026
Source data
Overview
Missing authorization in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
Impact & technical details
Elevation of Privilege
What privileges could be gained by an attacker who successfully exploited the vulnerability? The attacker would be able to take over the mailboxes of all Exchange users, attackers can send emails, read emails, download attachments.
How could an attacker exploit this vulnerability? An attacker authenticated to an affected Exchange server as a member of a highly privileged role group could send a specially crafted request over the network to bypass mailbox authorization checks. Successful exploitation could allow the attacker to access or modify another user's mailbox content without user interaction.
- CVSS base score
- 9.1 / 10
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/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.
GTP recommendation · Rule-based guidance
Recommended next step
Review affected Microsoft products and apply the applicable security updates through your organization's normal patch-management process. Confirm availability and prerequisites in the Microsoft advisory.
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 remediation guidance (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
- Microsoft security update · 5121608 (opens in a new tab)
- Microsoft remediation guidance (opens in a new tab)
Managed by GTP?
Griffin Technology Partners managed customers may receive additional environment-specific security guidance and remediation assistance through their managed services relationship.
Security bulletins are provided for informational purposes and compiled from authoritative public sources. Vulnerability applicability varies by environment. Validate affected products, configuration, compatibility requirements, and vendor guidance before making production changes.