---
id: CVE-2026-55008
title: Microsoft Exchange Server Spoofing Vulnerability
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.
severity: critical
cvss: 9.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C'
cvssSource: cna
cwe:
  - CWE-79
vendor: Microsoft
product: Microsoft Exchange Server 2016 Cumulative Update 23
affected:
  - exchange_server_2016_cumulative_update_23 >= 15.01.0.0 < 15.01.2507.071
  - exchange_server_2019_cumulative_update_14 >= 15.02.0.0 < 15.02.1544.043
  - exchange_server_2019_cumulative_update_15 >= 15.02.0.0 < 15.02.1748.048
  - exchange_server_subscription_edition_rtm >= 15.02.0.0 < 15.02.2562.045
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-07-15T03:57:27.773430Z'
published: '2026-07-14'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T22:29:02.641Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-55008'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55008'
    label: Microsoft Exchange Server Spoofing Vulnerability
tags:
  - cve.org
epss: 0.00863
epssPercentile: 0.57094
ingestedAt: '2026-09-08T17:06:31.929Z'
---

## Overview

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.

## Affected

- `exchange_server_2016_cumulative_update_23 >= 15.01.0.0 < 15.01.2507.071`
- `exchange_server_2019_cumulative_update_14 >= 15.02.0.0 < 15.02.1544.043`
- `exchange_server_2019_cumulative_update_15 >= 15.02.0.0 < 15.02.1748.048`
- `exchange_server_subscription_edition_rtm >= 15.02.0.0 < 15.02.2562.045`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.