CVE-2021-33766

high

Description

Microsoft Exchange Server Information Disclosure Vulnerability

References

https://www.zerodayinitiative.com/advisories/ZDI-21-798/

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-33766

https://www.tenable.com/blog/aa22-257a-cybersecurity-joint-advisory-on-iranian-islamic-revolutionary-guard-ransomware

https://github.com/demossl/CVE-2021-33766-ProxyToken

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-33766

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-33766

https://euvd.enisa.europa.eu/vulnerability/EUVD-2021-20443

Details

Source: Mitre, NVD

Published: 2021-07-14

Updated: 2026-08-10

Named Vulnerability: ProxyTokenKnown Exploited Vulnerability (KEV)

Risk Information

CVSS v2

Base Score: 5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N

Severity: Medium

CVSS v3

Base Score: 7.5

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

Severity: High

EPSS

EPSS: 0.98176