Auth bypass in Microsoft Exchange_server
CVE-2026-45503
Improper authorization in Microsoft Exchange Server allows an authorized attacker to disclose information over a network.
EPSS: 0.004 (36.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
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
- secure@microsoft.com (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-45503?
- CVE-2026-45503 is a high-severity vulnerability in Microsoft Exchange_server, classified under Improper Authorization. CVSS score: 8.1/10. Published 2026-06-09.
- How severe is CVE-2026-45503?
- High severity. CVSS v3 base score is 8.1 out of 10.