CVE-2021-33766
Act now ● On CISA KEV — actively exploited
Actively exploited — on the CISA KEV list.
CVSS base
7.3
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
EPSS — probability of exploitation (30 days)
98.1%
99.9th percentile
CISA KEV
Listed
Added 2022-01-18 · patch by 2022-02-01
Weakness / dates
—
Published 2021-07-14 · modified 2026-08-10
CVSS breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
| Attack Vector | N | Network |
| Attack Complexity | L | Low |
| Privileges Required | N | None |
| User Interaction | N | None |
| Scope | U | Unchanged |
| Confidentiality | L | Low |
| Integrity | L | Low |
| Availability | L | Low |
Timeline
- 2021-07-14 — Published (NVD)
- 2022-01-18 — Added to CISA KEV (actively exploited)
- 2022-02-01 — CISA patch-by deadline
- 2026-08-10 — Last modified (NVD)
Description
Microsoft Exchange Server Information Disclosure Vulnerability