What is CVE-2018-8265?

CVE-2018-8265 is a high-severity vulnerability in Microsoft Exchange Server, classified under Improper Input Validation. CVSS score: 7.8/10. Published 2018-10-10.

How severe is CVE-2018-8265?

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

Improper input validation in Microsoft Exchange Server

CVE-2018-8265

A remote code execution vulnerability exists in the way Microsoft Exchange software parses specially crafted email messages, aka "Microsoft Exchange Remote Code Execution Vulnerability." This affects Microsoft Exchange Server.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published 2018-10-10 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.193 (97.3th percentile), scored 2026-10-19.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 97th percentile — 97.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.253 · newest: 0.193 · change: -0.060

Affected products

Microsoft Exchange Server — versions 2013, 2016
Microsoft Exchange Server — versions 2013 Cumulative Update 21, 2016 Cumulative Update 10

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

www.securityfocus.com/bid/105491 (VDB Entry, Third Party Advisory, vdb-entry)
portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8265 (Patch, Vendor Advisory)
www.securitytracker.com/id/1041836 (VDB Entry, Third Party Advisory, vdb-entry)

Frequently asked questions

What is CVE-2018-8265?: CVE-2018-8265 is a high-severity vulnerability in Microsoft Exchange Server, classified under Improper Input Validation. CVSS score: 7.8/10. Published 2018-10-10.
How severe is CVE-2018-8265?: High severity. CVSS v3 base score is 7.8 out of 10.