Exploited· due 2022-05-03used in ransomware
CVE-2021-26857
Microsoft Exchange Server
Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.
Exploitation status
- CISA has confirmed this is being exploited in the wild. That is an observation of real attacks, not a prediction.
- It is known to have been used in ransomware campaigns.
- US federal civilian agencies are required to remediate it by 2022-05-03. That deadline does not bind private companies, but it is a reasonable benchmark for how urgently CISA views it.
Required action
Apply updates per vendor instructions.
CISA’s wording, unedited.
Scoring
- CVSS
- Not yet scored
Dates
- Published
- 2021-11-03
- Added to KEV
- 2021-11-03
- Remediation due
- 2022-05-03
- Sources
- CISA KEV