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Fencer Vulns
high 7.8

CVE-2021-31198 json

Microsoft Exchange Server Remote Code Execution Vulnerability

published 2021-05-11 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-18111

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
4.9%
EPSS 4.9% chance of exploitation in 30 days, percentile 92%
public exploits
0
none known

Summary

Microsoft Exchange Server Remote Code Execution Vulnerability

Patch / fix

  • Microsoft Microsoft Exchange Server 2019 Cumulative Update 9 15.02.0858.012
  • Microsoft Microsoft Exchange Server 2016 Cumulative Update 20 15.01.2242.010
  • Microsoft Microsoft Exchange Server 2013 Cumulative Update 23 15.00.1497.018
  • Microsoft Microsoft Exchange Server 2016 Cumulative Update 19 15.01.2176.014
  • Microsoft Microsoft Exchange Server 2019 Cumulative Update 8 15.02.0792.015

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
20 mo ago

Exploit prediction

4.87% chance of exploitation in the next 30 days, higher than 92% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
NVD 2.0 6.8 AV:N/AC:M/Au:N/C:P/I:P/A:P

Affected products

  • Microsoft Microsoft Exchange Server 2019 Cumulative Update 9
  • Microsoft Microsoft Exchange Server 2016 Cumulative Update 20
  • Microsoft Microsoft Exchange Server 2013 Cumulative Update 23
  • Microsoft Microsoft Exchange Server 2016 Cumulative Update 19
  • Microsoft Microsoft Exchange Server 2019 Cumulative Update 8

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code
  • CWE-20 Improper Input Validation
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.