CVE-2021-26858highunder attackransomware

CVE-2021-26858: high-severity vulnerability in Microsoft Exchange Server 2013 Cumulative…

Microsoft Exchange Server Remote Code Execution Vulnerability

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73Vexday Risk Score

Prioritize patching. It under exploitation confirmed by CISA and 2 threat group(s) use it.

ssvc Actcvss 7.8epss 94%
from disclosure to weapon
Published on NVDMar 2
CISA KEV+246d
Who exploits it — 2

Groups known to exploit this vulnerability (MITRE ATT&CK attribution).

APT / StateMagic Hound🇮🇷 MITRE ATT&CK
APT / StateThreat Group-3390🇨🇳 MITRE ATT&CK
Action required by CISAfederal deadline: 2022-05-03

Apply updates per vendor instructions.

In short

A critical flaw in Microsoft Exchange Server allows attackers to run malicious code on vulnerable servers without needing valid credentials. This puts email systems and sensitive data at serious risk.

Technical detail

An unauthenticated remote attacker can exploit improper validation of user input in the Exchange Server backend to execute arbitrary code with system privileges. The vulnerability requires network access to the Exchange service but no prior authentication; successful exploitation leads to complete system compromise.

Summary generated and translated by AI from the official description.

The full analysis of this CVE is available in Portuguese →

Microsoft Exchange Server Remote Code Execution Vulnerability
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C
Affected products
Microsoft · Microsoft Exchange Server 2013 Cumulative Update 21Microsoft · Microsoft Exchange Server 2013 Cumulative Update 22Microsoft · Microsoft Exchange Server 2013 Cumulative Update 23Microsoft · Microsoft Exchange Server 2016 Cumulative Update 10Microsoft · Microsoft Exchange Server 2016 Cumulative Update 11Microsoft · Microsoft Exchange Server 2016 Cumulative Update 12Microsoft · Microsoft Exchange Server 2016 Cumulative Update 13Microsoft · Microsoft Exchange Server 2016 Cumulative Update 14Microsoft · Microsoft Exchange Server 2016 Cumulative Update 15Microsoft · Microsoft Exchange Server 2016 Cumulative Update 16Microsoft · Microsoft Exchange Server 2016 Cumulative Update 17Microsoft · Microsoft Exchange Server 2016 Cumulative Update 18Microsoft · Microsoft Exchange Server 2016 Cumulative Update 19Microsoft · Microsoft Exchange Server 2016 Cumulative Update 8Microsoft · Microsoft Exchange Server 2016 Cumulative Update 9Microsoft · Microsoft Exchange Server 2019Microsoft · Microsoft Exchange Server 2019 Cumulative Update 1Microsoft · Microsoft Exchange Server 2019 Cumulative Update 2Microsoft · Microsoft Exchange Server 2019 Cumulative Update 3Microsoft · Microsoft Exchange Server 2019 Cumulative Update 4Microsoft · Microsoft Exchange Server 2019 Cumulative Update 5Microsoft · Microsoft Exchange Server 2019 Cumulative Update 6Microsoft · Microsoft Exchange Server 2019 Cumulative Update 7Microsoft · Microsoft Exchange Server 2019 Cumulative Update 8
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