CVE-2021-34453
Microsoft Exchange Server Denial of Service Vulnerability
HIGH
7.5
CVSS Score
Published: October 13, 2021 at 12:26 AM UTC
Updated: June 17, 2026 at 03:55 AM UTC
1 product affected across 1 vendorExchange Server
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Severity
HIGH7.5
Exploit prediction
EPSS 3%
SSVC
No known exploit
Description
Microsoft Exchange Server Denial of Service Vulnerability
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
15.0.0 ≤ v < 15.01.2375.01215.01.0 ≤ v < 15.01.2308.01515.02.0 ≤ v < 15.02.0922.01415.02.0 ≤ v < 15.02.0986.00915.0.015.01.015.02.020162016 cumulative_update_212016 cumulative_update_2220192019 cumulative_update_102019 cumulative_update_11
Affected range stops below 15.01.2308.015, so it looks safe — our inference, not a vendor statement
Affected range stops below 15.01.2375.012, so it looks safe — our inference, not a vendor statement
Affected range stops below 15.02.0922.014, so it looks safe — our inference, not a vendor statement
Affected range stops below 15.02.0986.009, so it looks safe — our inference, not a vendor statement
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
Patch and advisory references
References (1)
x_refsource_MISCPatchVendor Advisory
Source: [email protected]
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34453SSVC — Action Prioritization
SSVCNo known exploitAutomatablePartial impact
SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.
CVSS
7.5HIGHmicrosoft
Vector?
Quick Info
StatusMODIFIED
CWE
NVD-CWE-noinfo
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