What is CVE-2023-21763?

CVE-2023-21763 is a high-severity vulnerability in Microsoft Exchange Server, classified under Untrusted Search Path. CVSS score: 7.8/10. Published 2023-01-10.

How severe is CVE-2023-21763?

High severity. CVSS v3 base score is 7.8 out of 10.

Vulnerability in Microsoft Exchange Server

CVE-2023-21763

Microsoft Exchange Server Elevation of Privilege Vulnerability

Published 2023-01-10 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.006 (46.5th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 46.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Microsoft Exchange Server — versions 2016, 2019
Microsoft Exchange Server 2016 Cumulative Update 23 — versions 15.01.0
Microsoft Exchange Server 2019 Cumulative Update 11 — versions 15.02.0
Microsoft Exchange Server 2019 Cumulative Update 12 — versions 15.02.0

Weakness classification (CWE)

CWE-426 — Untrusted Search Path

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21763 (vendor-advisory)

Frequently asked questions

What is CVE-2023-21763?: CVE-2023-21763 is a high-severity vulnerability in Microsoft Exchange Server, classified under Untrusted Search Path. CVSS score: 7.8/10. Published 2023-01-10.
How severe is CVE-2023-21763?: High severity. CVSS v3 base score is 7.8 out of 10.