CVE-2021-26857highunder attackransomwareCWE-502

CVE-2021-26857: high-severity vulnerability in Microsoft Exchange Server 2010 Service Pack 3

Microsoft Exchange Server Remote Code Execution Vulnerability

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98Vexday Risk Score

Prioritize patching. It under exploitation confirmed by CISA, has a public proof of concept and 2 threat group(s) use it.

ssvc Actcvss 7.8epss 96%
from disclosure to weapon9 days
Published on NVDMar 2
1st PoC+9d
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 vulnerability in Microsoft Exchange Server allows attackers to execute arbitrary code remotely on vulnerable servers. This is critical because Exchange is widely used for email management, and compromise could lead to complete server takeover and data theft.

Technical detail

CWE-502 (Deserialization of Untrusted Data) in Microsoft Exchange Server permits remote code execution through malicious serialized objects sent to vulnerable endpoints. The attack requires network access to the Exchange service but no authentication; exploitation results in system-level code execution within the service context.

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 2010 Service Pack 3Microsoft · Microsoft Exchange Server 2013 Cumulative Update 21Microsoft · Microsoft Exchange Server 2013 Cumulative Update 22Microsoft · Microsoft Exchange Server 2013 Cumulative Update 23Microsoft · Microsoft Exchange Server 2013 Service Pack 1Microsoft · 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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