Live › vulnerability › CVE-2021-26858
Go to dashboardMicrosoft Exchange Server has an unspecified flaw that allows remote code execution, and it is part of the ProxyLogon chain. Attackers are exploiting it in the wild and it is tagged as used in ransomware campaigns.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 19:11 UTC, 3h before NVD. All times on this page are UTC.
Apply updates per vendor instructions.
| Product | Ecosystem | Affected | Fixed in |
|---|---|---|---|
| Microsoft Exchange Server | vendor | – | – |
Unknown from the sources. In the analyst’s queue.
Apply the Microsoft updates for Exchange Server per vendor instructions (CISA KEV required action); the specific build numbers are not in the sources.
Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.
CISA required action: Apply updates per vendor instructions.
This page as .md · .json · in your agent: get_signal("CVE-2021-26858")
CISA KEV catalog, Creative Commons 0 · EPSS scores by FIRST, used with attribution · NVD data is provided by NIST and is public domain. Posts quoted belong to their authors.