Vulnerability · Published Feb 10, 2026 · Assigned by microsoft
CVE-2026-21527Microsoft Exchange Server Spoofing Vulnerability
Medium 6.5
In plain English
A medium-severity insufficient verification of data authenticity 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 8.1% (higher than 95% of all known vulnerabilities).
Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)8.1%top 5.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 23 | 15.01.0.0 – before 15.01.2507.066 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 14 | 15.02.0.0 – before 15.02.1544.039 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 15 | 15.02.0.0 – before 15.02.1748.043 |
| Microsoft | Microsoft Exchange Server Subscription Edition RTM | 15.02.0.0 – before 15.02.2562.037 |
Weakness: CWE-451, CWE-345, CWE-1286 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C
References
- Microsoft Exchange Server Spoofing Vulnerability vendor-advisory, patch