Is CVE-2021-31207 in the CISA KEV catalog?

Yes. CVE-2021-31207 is on the CISA Known Exploited Vulnerabilities list, added 2021-11-03, and has known ransomware campaign use.

What is the CVSS severity of CVE-2021-31207?

CVE-2021-31207 has a CVSS v3 base score of 6.6 (MEDIUM).

What is the EPSS score for CVE-2021-31207?

CVE-2021-31207 has an EPSS score of 99.78% (100th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2021-31207

MEDIUMCISA KEVEPSS 100th pctl

6.6

CVSS v3

NVD

Description

Microsoft Exchange Server Security Feature Bypass Vulnerability

CWE-434Unrestricted File Upload

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityHigh

Privileges RequiredHigh

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Exploit Intelligence

99.78%probability of exploitation in 30 days

100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Microsoft Exchange Server Security Feature Bypass Vulnerability

Microsoft Exchange Server contains an unspecified vulnerability that allows for security feature bypass.

Apply updates per vendor instructions.

Remediation due: 2021-11-17

Associated with ransomware campaigns

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-30.