Vulnerability · Published Sep 8, 2026 · Assigned by microsoft
CVE-2026-69378Microsoft Exchange Server Denial of Service Vulnerability
High 7.5
In plain English
A high-severity security flaw in Microsoft Exchange Server 2016 Cumulative Update 23 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 68% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)1.2%top 32.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Uncontrolled recursion in Microsoft Exchange Server allows an unauthorized attacker to deny service over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 23 | 15.01.0.0 – before 15.01.2507.073 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 14 | 15.02.0.0 – before 15.02.1544.046 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 15 | 15.02.0.0 – before 15.02.1748.051 |
| Microsoft | Microsoft Exchange Server Subscription Edition RTM | 15.02.0.0 – before 15.02.2562.049 |
Weakness: CWE-674 · Vector: 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
References
- Microsoft Exchange Server Denial of Service Vulnerability vendor-advisory, patch