CVE-2021-26858.

Source-reported disclosure and enrichment record.

SEVERITY / CVSSUnscoredNo severity score in this snapshot.

EXPLOITATION STATUSCISA known exploitedAdded Nov 03, 2021

RECORD STATUSAwaiting NVD dataModified Nov 03, 2021

Disclosure summary

Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.

CISA remediation guidance

Apply updates per vendor instructions.

Original records & references

NIST NVD record
CVE Program record
CISA KEV catalog entry

PUBLISHED 2021-11-03T00:00:00-04:00
MODIFIED 2021-11-03T00:00:00-04:00
INGESTED 2026-10-06T11:42:59-04:00