CVE-2021-34453
Microsoft Exchange Server Denial of Service Vulnerability
Microsoft Exchange Server Denial of Service Vulnerability
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Microsoft Exchange Server Denial of Service Vulnerability
Microsoft Exchange Server Denial of Service Vulnerability
- Record
CVE-2021-34453- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C - Updated
- 2026-11-02
EUVDEUVD-2021-21108
Microsoft Exchange Server Denial of Service Vulnerability
- Record
EUVD-2021-21108- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-jh7x-v5rp-ggfr
Microsoft Exchange Server Denial of Service Vulnerability
Microsoft Exchange Server Denial of Service Vulnerability
- Record
GHSA-jh7x-v5rp-ggfr- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
NVD
Microsoft Exchange Server Denial of Service Vulnerability
- Record
CVE-2021-34453- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:N/A:P - Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-34453 is a high vulnerability (CVSS 7.5) in Microsoft Exchange Server, published October 13, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.83%, the 86th percentile. No source names a fixed version.