CVE-2021-31209
Microsoft Exchange Server Spoofing Vulnerability
6.5 Medium
Microsoft Exchange Server Spoofing Vulnerability
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- Low
- Availability
- None
Exploit likelihood
2.63%Up 2.2 points since May 12, 2021
What each source reports
CVE List Score used
Microsoft Exchange Server Spoofing Vulnerability
Microsoft Exchange Server Spoofing Vulnerability
- Record
CVE-2021-31209- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N/E:U/RL:O/RC:C - Weakness
- CWE-290
- Updated
- 2026-11-02
EUVDEUVD-2021-18122
Microsoft Exchange Server Spoofing Vulnerability
- Record
EUVD-2021-18122- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N/E:U/RL:O/RC:C - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-v623-3qmp-8rrh
Microsoft Exchange Server Spoofing Vulnerability
Microsoft Exchange Server Spoofing Vulnerability
- Record
GHSA-v623-3qmp-8rrh- CVSS 3.1
- 8.1 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N - Weakness
- CWE-290
- Updated
- 2026-11-02
NVD
Microsoft Exchange Server Spoofing Vulnerability
- Record
CVE-2021-31209- CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N - CVSS 3.1
- 8.1 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N - CVSS 2.0
- 5.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:N - Weakness
- CWE-290
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-31209 is a medium vulnerability (CVSS 6.5) in Microsoft Exchange Server, published May 11, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.63%, the 85th percentile. No source names a fixed version.