CVE-2021-33766

Microsoft Exchange Server Information Disclosure Vulnerability

Microsoft Exchange Server Information Disclosure Vulnerability

Affected

Microsoft · Microsoft Exchange Server 2013 Cumulative Update 23 · Microsoft Exchange Server 2016 Cumulative Update 19 · Microsoft Exchange Server 2016 Cumulative Update 20 · Microsoft Exchange Server 2019 Cumulative Update 8 · Microsoft Exchange Server 2019 Cumulative Update 9

CVSS v3.1 NVD

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

CVSS v3.1 MICROSOFT

7.3 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

CVSS v2.0 NVD

5.0 MEDIUMAV:N/AC:L/Au:N/C:P/I:N/A:N

EPSS

98.18% chance of exploitation in the next 30 days, 100th percentile

CISA KEV

added 2022-01-18

Nuclei

high

Published

2021-07-14

Updated

2026-08-10

Proof-of-concept exploits (2)

• bhdresh/CVE-2021-3376647★ · 2021-10-14
• demossl/CVE-2021-33766-ProxyToken10★ · 2021-09-15

Nuclei templates (1)

• projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-33766.yaml

Security advisories

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766
• https://www.zerodayinitiative.com/advisories/ZDI-21-798

References

• CVE Record
• NVD entry

Related

• CVE-2017-0199
• CVE-2017-8759
• CVE-2018-11776