ProxyLogon (CVE-2021-26855): 2021’s Top Contender for Vulnerability for the Year (It’s March...)

CVE

CVE-2021-26855

Published

2021-03-10 00:00

Collected

2026-07-08 02:00

---
id: 4079
title: "ProxyLogon (CVE-2021-26855): 2021’s Top Contender for Vulnerability for the Year (It’s March...)"
cve: CVE-2021-26855
source_domain: bishopfox.com
source_url: "https://bishopfox.com/blog/proxylogon-cve-2021-26855"
published_at: "2021-03-10T00:00:00Z"
tags: ["zero-day", "ssrf", "proxylogon", "cve-2021-26855", "microsoft-exchange", "webshell"]
phying_url: "https://phying.com/item/4079"
lang: en
---

# ProxyLogon (CVE-2021-26855): 2021’s Top Contender for Vulnerability for the Year (It’s March...)

## Summary

The ProxyLogon attack chain — CVE-2021-26855 and three more Exchange flaws — hit 30,000+ organizations, letting attackers steal email and plant web shells.

## Intelligence Metadata

- **Sources:** bishopfox.com
- **CVE:** CVE-2021-26855
- **Published:** 2021-03-10T00:00:00Z
- **Original:** https://bishopfox.com/blog/proxylogon-cve-2021-26855
- **Phying News:** https://phying.com/item/4079