CVE-2020-17143
HighMicrosoft Exchange Server Information Disclosure Vulnerability
Published Dec 9, 2020 · Updated Jun 9, 2026
Key Facts
Patch immediately- CVE-2020-17143 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting Exchange Server (Microsoft), Microsoft Exchange Server 2013 Cumulative Update 23, Microsoft Exchange Server 2016 Cumulative Update 17 and 3 more products.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 71% probability of exploitation in the next 30 days.
- Fixed versions are available, including Microsoft Exchange Server 2013 Cumulative Update 23 publication, Microsoft Exchange Server 2016 Cumulative Update 17 publication, Microsoft Exchange Server 2016 Cumulative Update 18 publication.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
8.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
71%
Higher than 99.3% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
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Description
Microsoft Exchange Server Information Disclosure Vulnerability
Affected Products
10 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Exchange ServerMicrosoft | 2013-cumulative_update_23, 2016-cumulative_update_17, 2016-cumulative_update_18, 2019-cumulative_update_6, 2019-cumulative_update_7 | n/a |
| Microsoft Exchange Server 2013 Cumulative Update 23 | >= 15.00.0 | publication |
| Microsoft Exchange Server 2016 Cumulative Update 17 | >= 15.01.0 | publication |
| Microsoft Exchange Server 2016 Cumulative Update 18 | >= 15.01.0 | publication |
| Microsoft Exchange Server 2019 Cumulative Update 6 | >= 15.02.0 | publication |
Patched Releases
Microsoft Exchange Server 2013 Cumulative Update 23
publication
Microsoft Exchange Server 2016 Cumulative Update 17
publication
Microsoft Exchange Server 2016 Cumulative Update 18
publication
Microsoft Exchange Server 2019 Cumulative Update 6
publication
Microsoft Exchange Server 2019 Cumulative Update 7
publication
Timeline
Publicly disclosed
Dec 9, 2020
Last updated
Jun 9, 2026
References
FAQ
Common Questions.
Microsoft Exchange Server Information Disclosure Vulnerability
Affected: Exchange Server (Microsoft) versions 2013-cumulative_update_23, 2016-cumulative_update_17, 2016-cumulative_update_18, 2019-cumulative_update_6, 2019-cumulative_update_7; Microsoft Exchange Server 2013 Cumulative Update 23 versions >= 15.00.0; Microsoft Exchange Server 2016 Cumulative Update 17 versions >= 15.01.0, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Microsoft Exchange Server 2013 Cumulative Update 23 publication, Microsoft Exchange Server 2016 Cumulative Update 17 publication, Microsoft Exchange Server 2016 Cumulative Update 18 publication.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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