Microsoft Exchange Server
CVE-2026-69378 — Microsoft Exchange Server Denial of Service Vulnerability
Executive Summary
Uncontrolled recursion in Microsoft Exchange Server allows an unauthorized attacker to deny service over a network.
Overview
7.5
CVSS HIGH
Important
MS Severity
Not Exploited
MS Exploit Status
Less Likely
MS Exploit Likelihood
CVSS Vector
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
None
INTEGRITY
None
AVAILABILITY
High
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 6.5
EPSS Score
No EPSS score available for this CVE.
View on FIRST.orgAffected Products
4 affected products
| Product | KB Article | Severity | Impact | Restart Required |
|---|---|---|---|---|
| Microsoft Exchange Server 2016 Cumulative Update 23 | 5121611 (Security Update) |
Important | Denial of Service | Yes |
| Microsoft Exchange Server 2019 Cumulative Update 14 | 5121610 (Security Update) |
Important | Denial of Service | Yes |
| Microsoft Exchange Server 2019 Cumulative Update 15 | 5121609 (Security Update) |
Important | Denial of Service | Yes |
| Microsoft Exchange Server Subscription Edition RTM | 5121608 (Security Update) |
Important | Denial of Service | Yes |
Patches
4 patches
| Article | Type | Restart |
|---|---|---|
5121611 |
Security Update | Yes |
5121610 |
Security Update | Yes |
5121609 |
Security Update | Yes |
5121608 |
Security Update | Yes |
Exploits & PoC
No public exploit or PoC has been linked for this CVE yet. When available, references are sourced from public repositories and may be unverified or non-functional — review carefully before use.
Detection Rules
No public Sigma or Nuclei detection rule has been mapped to this CVE yet. Coverage is concentrated on exploited / high-profile vulnerabilities; check SigmaHQ for updates.
Acknowledgments
References
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