Overview
Microsoft Exchange Server contains an information disclosure vulnerability which can allow an unauthenticated attacker to steal email traffic from target.
https://nvd.nist.gov/vuln/detail/CVE-2021-33766
Key Details
| Property | Value |
|---|---|
| CVE ID | CVE-2021-33766 |
| Vendor / Product | Microsoft — Exchange Server |
| NVD Published | 2021-07-14 |
| NVD Last Modified | 2025-10-29 |
| CVSS 3.1 Score | 7.3 |
| CVSS 3.1 Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L |
| Severity | HIGH |
| CISA KEV Added | 2022-01-18 |
| CISA KEV Deadline | 2022-02-01 |
| Known Ransomware Use | No |
CVSS 3.1 Breakdown
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low
Required Action
CISA BOD 22-01 Deadline: 2022-02-01.
Apply updates per vendor instructions.
Timeline
| Date | Event |
|---|---|
| 2022-01-18 | Added to CISA Known Exploited Vulnerabilities catalog |
| 2022-02-01 | CISA BOD 22-01 remediation deadline |
References
| Resource | Type |
|---|---|
| NVD — CVE-2021-33766 | Vulnerability Database |
| CISA KEV Catalog Entry | US Government |