CVE-2021-34453 json
Microsoft Exchange Server Denial of Service Vulnerability
published 2021-10-13 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-21108
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 2.8%
- EPSS 2.8% chance of exploitation in 30 days, percentile 86%
- public exploits
- 0
- none known
Summary
Microsoft Exchange Server Denial of Service Vulnerability
Patch / fix
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 11 15.02.0986.009
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 10 15.02.0922.014
- Microsoft Microsoft Exchange Server 2016 Cumulative Update 21 15.01.2308.015
- Microsoft Microsoft Exchange Server 2016 Cumulative Update 22 15.01.2375.012
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 2 y ago
Exploit prediction
2.83% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.5 | 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 |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVD | 2.0 | 5.0 | AV:N/AC:L/Au:N/C:N/I:N/A:P |
Affected products
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 11
- Microsoft Microsoft Exchange Server 2019 Cumulative Update 10
- Microsoft Microsoft Exchange Server 2016 Cumulative Update 21
- Microsoft Microsoft Exchange Server 2016 Cumulative Update 22
Classification
- Technology feeds
References
-
portal.msrc.microsoft.com
/en-US/security-guidance/advisory/CVE-2021-34453
patch, vendor-advisory
Sources
- CVE List CVE-2021-34453
- NVD CVE-2021-34453
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.