Exploited· due 2022-02-017.3highHigh
CVE-2021-33766
Microsoft Exchange Server
Microsoft Exchange Server Information Disclosure Vulnerability
Exploitation status
- CISA has confirmed this is being exploited in the wild. That is an observation of real attacks, not a prediction.
- US federal civilian agencies are required to remediate it by 2022-02-01. That deadline does not bind private companies, but it is a reasonable benchmark for how urgently CISA views it.
- A vendor advisory or patch reference has been published.
Required action
Apply updates per vendor instructions.
CISA’s wording, unedited.
What the metrics mean
- It is reachable over a network, without needing local access.
- For an attacker who can reach it, no special conditions are needed to exploit it.
- To exploit it, no account is needed.
- Beyond that, no action by a user is required.
Scoring
- CVSS
- 7.3 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L- Assigned by
- secure@microsoft.com
Dates
- Published
- 2021-07-14
- Last modified
- 2026-08-10
- Added to KEV
- 2022-01-18
- Remediation due
- 2022-02-01
- Sources
- CISA KEV, NVD
Affected products
- Microsoft Exchange Server2013, 2016, 2019
As listed in the NVD configuration data. Not a statement about your estate.