---
id: CVE-2026-87696
title: >-
  Improper verification of cryptographic signature in Microsoft Exchange Server
  allows an authorized attacker to elevate privileges over a network.
summary: >-
  Improper verification of cryptographic signature in Microsoft Exchange Server
  allows an authorized attacker to elevate privileges over a network.
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-347
published: '2026-10-13'
updated: '2026-10-13'
sourceUpdated: '2026-10-13T21:19:37.530'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-87696'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-87696'
    label: secure@microsoft.com
tags:
  - nvd
ingestedAt: '2026-10-13T19:43:29.201Z'
---

## Overview

Improper verification of cryptographic signature in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.

## Remediation

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