OnlyFm252
Microsoft Exchange Server

CVE-2020-0688 — Microsoft Exchange Validation Key Remote Code Execution Vulnerability

Important CVSS 8.8 EPSS 0.99965 2020-02 archive

Executive Summary

A remote code execution vulnerability exists in Microsoft Exchange Server when the server fails to properly create unique keys at install time. Knowledge of a the validation key allows an authenticated user with a mailbox to pass arbitrary objects to be deserialized by the web application, which runs as SYSTEM. The security update addresses the vulnerability by correcting how Microsoft Exchange creates the keys during install.

Overview

8.8
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
More Likely
MS Exploit Likelihood
Category Remote Code Execution
Released Feb 11 2020
Last Updated Feb 11 2020
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.99965 — 0.99977 percentile
NVD CVSS 8.8 HIGH — differs from MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
Low
USER INTERACTION
None
SCOPE
Unchanged

EPSS Score

0.99965
probability of exploitation in the next 30 days
0.99977 percentile - updated 2026-06-21
View on FIRST.org

Affected Products

6 affected products
Product KB Article Severity Impact Restart Required
Microsoft Exchange Server 2010 Service Pack 3 Update Rollup 30 4536989 (Security Update) Important Remote Code Execution Maybe
Microsoft Exchange Server 2013 Cumulative Update 23 4536988 (Security Update) Important Remote Code Execution Maybe
Microsoft Exchange Server 2016 Cumulative Update 14 4536987 (Security Update) Important Remote Code Execution Maybe
Microsoft Exchange Server 2016 Cumulative Update 15 4536987 (Security Update) Important Remote Code Execution Maybe
Microsoft Exchange Server 2019 Cumulative Update 3 4536987 (Security Update) Important Remote Code Execution Maybe
Microsoft Exchange Server 2019 Cumulative Update 4 4536987 (Security Update) Important Remote Code Execution Maybe

Patches

3 patches
Article Type Restart
4536989 Security Update Maybe
4536988 Security Update Maybe
4536987 Security Update Maybe

Known Exploits

On This Page