Vulnerability in Microsoft Exchange Server
CVE-2026-21527
User interface (ui) misrepresentation of critical information in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.080 (94.6th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 95th percentile — 94.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.077 · newest: 0.080 · change: +0.003
Affected products
- Microsoft Exchange Server — versions 2016, 2019
- Microsoft Exchange Server Subscription Edition
- Microsoft Exchange Server 2016 Cumulative Update 23 — versions 15.01.0.0
- Microsoft Exchange Server 2019 Cumulative Update 14 — versions 15.02.0.0
- Microsoft Exchange Server 2019 Cumulative Update 15 — versions 15.02.0.0
- Microsoft Exchange Server Subscription Edition Rtm — versions 15.02.0.0
Weakness classification (CWE)
References
- Microsoft Exchange Server Spoofing Vulnerability (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-21527?
- CVE-2026-21527 is a medium-severity vulnerability in Microsoft Exchange Server, classified under Insufficient Verification of Data Authenticity. CVSS score: 6.5/10. Published 2026-02-10.
- How severe is CVE-2026-21527?
- Medium severity. CVSS v3 base score is 6.5 out of 10.