VulnerabilityModified

CVE-2021-27078

Microsoft Exchange Server Remote Code Execution Vulnerability

CRITICAL 9.1EPSS 21.6%

Does this matter?

EPSS puts the probability of exploitation in the next 30 days at 21.6%, higher than 98% of all known CVEs. Patch or mitigate before the next change window.

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

CVSS 3.1: 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
EPSS: 21.59% probability · 98th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Affected: microsoft/exchange server
Source: secure@microsoft.com

EPSS trend

EPSS moved from 21.6% on 21 September 2026 to 21.6% on 26 October 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-27078
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-27078Patch, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.