Cyber Resilience

CVE-2021-31198

High

Published: 11 May 2021

Published
11 May 2021
Modified
28 February 2025
KEV Added
Patch
CVSS Score v3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS Score 0.0396 88.6th percentile
Risk Priority 18 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-31198 is a high-severity Improper Input Validation (CWE-20) vulnerability in Microsoft Exchange Server. Its CVSS base score is 7.8 (High).

Operationally, ranked in the top 11.4% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Microsoft Exchange Server Remote Code Execution Vulnerability

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

microsoft
exchange server
2013, 2016, 2019

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-20 CWE-94

Directly implements checks on information inputs to reject invalid data before processing.

addresses: CWE-20

Security testing and developer training directly verify and enforce proper input validation, reducing exploitability of injection and malformed-data weaknesses.

addresses: CWE-20

Security testing and evaluation at multiple SDLC stages directly detects missing or flawed input validation, with the required remediation process ensuring fixes are applied.

addresses: CWE-94

Makes persistent code injection into loaded programs impossible when the executable image itself resides on hardware-protected read-only media.

addresses: CWE-94

Dynamically generated code can be produced and executed inside the isolated chamber, preventing host compromise from code-injection payloads.

addresses: CWE-94

Directly prevents execution of attacker-supplied code written into data memory regions.

addresses: CWE-20

Spam protection mechanisms perform filtering and detection on inbound/outbound messages, directly compensating for missing or weak input validation of unsolicited content.

References