Critical CVSS 6.1 EPSS 0.02509 ⚠️ Exploited in the wild 2026-05 archive

Executive Summary

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.

Overview

6.1
CVSS MEDIUM
Critical
MS Severity
Exploited
MS Exploit Status
Exploitation Detected
MS Exploit Likelihood
Category Spoofing
Released May 12 2026
Last Updated May 12 2026
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.02509 — 0.82695 percentile
NVD CVSS 6.1 MEDIUM — differs from MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
USER INTERACTION
Required
SCOPE
Changed
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
None
EXPLOIT CODE MATURITY
Functional
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 7.5

EPSS Score

0.02509
probability of exploitation in the next 30 days
0.82695 percentile - updated 2026-06-21
View on FIRST.org

Affected Products

4 affected products
Product KB Article Severity Impact Restart Required
Microsoft Exchange Server 2016 Cumulative Update 23 5094144 (Security Update) Critical Spoofing Yes
Microsoft Exchange Server 2019 Cumulative Update 14 5094142 (Security Update) Critical Spoofing Yes
Microsoft Exchange Server 2019 Cumulative Update 15 5094140 (Security Update) Critical Spoofing Yes
Microsoft Exchange Server Subscription Edition RTM 5094139 (Security Update) Critical Spoofing Yes

Patches

4 patches
Article Type Restart
5094144 Security Update Yes
5094142 Security Update Yes
5094140 Security Update Yes
5094139 Security Update Yes

Known Exploits

Acknowledgments

Anonymous