CVE-2026-70571: Microsoft Exchange Server Remote Code Execution Vulnerability

Overview

Severity
High (CVSS 8.1)
CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Remote Code Execution
Exploit Status
Not Exploited
Exploitation Likelihood
More Likely
Patch Tuesday
2026-Oct
Released
2026-10-13

Description

Stack-based buffer overflow in Microsoft Exchange Server allows an unauthorized attacker to execute code over a network.

FAQ

How could an attacker exploit this vulnerability? An unauthenticated attacker could send a specially crafted email to an affected Exchange server, triggering an internal content-conversion process. Successful exploitation could allow the attacker to execute code on the server. Exploitation requires an attacker to have a deep understanding of the target environment and is not guaranteed to succeed. User interaction is not required. According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? Successful exploitation of this vulnerability requires an attacker to have a deep understanding of the system. Successful exploitation is not guaranteed and depends on a combination of factors that might include the environment, system configuration, and the presence of additional security measures.

Affected Products (4)

ESU

  • Microsoft Exchange Server 2019 Cumulative Update 15
  • Microsoft Exchange Server 2016 Cumulative Update 23
  • Microsoft Exchange Server 2019 Cumulative Update 14

Server Software

  • Microsoft Exchange Server Subscription Edition RTM

Security Updates (1)

Acknowledgments

<a href="https://x.com/xamroot">Max Toor</a> with Microsoft, <a href="https://smlijun.github.io/">DongJun Kim</a> with UIUC

Revision History

  • 2026-10-13: Information published.