What is CVE-2018-8153?

CVE-2018-8153 is a medium-severity vulnerability in Microsoft Exchange Server, classified under Authentication Bypass by Spoofing. CVSS score: 5.4/10. Published 2018-05-09.

How severe is CVE-2018-8153?

Medium severity. CVSS v3 base score is 5.4 out of 10.

Vulnerability in Microsoft Exchange Server

CVE-2018-8153

A spoofing vulnerability exists in Microsoft Exchange Server when Outlook Web Access (OWA) fails to properly handle web requests, aka "Microsoft Exchange Spoofing Vulnerability." This affects Microsoft Exchange Server.

Published 2018-05-09 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.034 (88.8th percentile), scored 2026-10-19.

Low probability of exploitation in the next 30 days, but still tracked. 89th percentile — 88.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.048 · newest: 0.034 · change: -0.013

Affected products

Microsoft Exchange Server — versions 2016
Microsoft Exchange Server — versions 2016 Cumulative Update 8, 2016 Cumulative Update 9

Weakness classification (CWE)

CWE-290 — Authentication Bypass by Spoofing

References

www.securityfocus.com/bid/104045 (VDB Entry, Third Party Advisory, vdb-entry)
www.securitytracker.com/id/1040850 (VDB Entry, Third Party Advisory, vdb-entry)
portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8153 (Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2018-8153?: CVE-2018-8153 is a medium-severity vulnerability in Microsoft Exchange Server, classified under Authentication Bypass by Spoofing. CVSS score: 5.4/10. Published 2018-05-09.
How severe is CVE-2018-8153?: Medium severity. CVSS v3 base score is 5.4 out of 10.