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CVEs

CVE-2021-26857

exploited in the wild
CVSS
9.8
Reports
6
First seen
Mar 3
Last seen
Apr 30
Affected product

Microsoft Exchange Server

Associated actors

APT28 ×1APT41 ×1Curious Serpens ×1Salt Typhoon ×1SHADOW-EARTH-053 ×1SheldIO ×1Storm-0501 ×1UNC4841 ×1Void Blizzard ×1

Recent reports

High

SHADOW-EARTH-053: China-Aligned Cyberespionage Campaign Against Asian Government and Defense Sectors

Trend Micro ResearchHigh

2025 Cloud Threat Hunting and Defense Landscape

Recorded Future InsiktHigh

Threat Intel Accelerates Detection and Response: OWASRRF Exchange Exploitation Case Study

Huntress BlogHigh

29 Most Frequently Exploited Vulnerabilities by Hackers (2020–2021): Joint Advisory

NICS TaiwanCritical

Microsoft Exchange Server Remote Code Execution Vulnerabilities (CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, CVE-2021-27065)

NICS TaiwanCritical

Multiple Vulnerabilities in Microsoft Exchange Server (CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, CVE-2021-27065)

GovCERT.HK

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