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CVE-2023-21709

32
FAUCET Score

CVE-2023-21709 is a critical Elevation of Privilege vulnerability affecting Microsoft Exchange Server. With a CVSS score of 9.8, it allows unauthenticated attackers to gain elevated privileges with low attack complexity, potentially leading to full compromise (confidentiality, integrity, and availability). While not currently listed in CISA's KEV catalog or having public exploit code in common repositories, it received significant community discussion and media coverage, indicating high awareness. Microsoft released a patch for this vulnerability during the August 2023 Patch Tuesday.

Impacted Technologies

VendorProductVersion(s)CPE
2016CPE matchmatch criteria
cpe:2.3:a:microsoft:exchange_server:2016:-:*:*:*:*:*:*
2016CPE matchmatch criteria
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_1:*:*:*:*:*:*
2016CPE matchmatch criteria
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_10:*:*:*:*:*:*
2016CPE matchmatch criteria
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_11:*:*:*:*:*:*
2016CPE matchmatch criteria
cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_12:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.86%
Probability of exploitation in next 30 days
EPSS Percentile
77.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0186 is in the 65th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

microsoftpatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: Microsoft Exchange Server 2019 Cumulative Update 12Fixed in: 15.02.1118.037
View patch
microsoftpatch availablevia msrc
Product: Microsoft Exchange Server 2016 Cumulative Update 23Fixed in: 15.01.2507.032
View patch
microsoftpatch availablevia msrc
Product: Microsoft Exchange Server 2019 Cumulative Update 13Fixed in: 15.02.1258.025
View patch

Vendor Advisories (1)

microsoft2023-Aug/CVE-2023-21709Important

Microsoft Exchange Server Elevation of Privilege Vulnerability

Aug 8, 2023

References

msrc.microsoft.com / update-guide/vulnerability/CVE-2023-21709
PatchVendor Advisory