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CVE-2021-27065

View the latest critical CVEs issued
This is a free service offered by Red Hot Cyber to the community. It allows you to view, on a single page, information about a single CVE from the National Vulnerability Database (NVD) and the National Institute of Standards and Technology (NIST) of the United States of America, the Forum of Incident Response and Security Teams (FIRST) regarding the EPSS score and percentile, data from the KEV catalog of the Cybersecurity and Infrastructure Security Agency (CISA), as well as selected resources from Red Hot Cyber and other international sources.

National Vulnerability Database Information

Description: Microsoft Exchange Server Remote Code Execution Vulnerability

CVSS Base Score: 7.8 (v3.1)

The **CVSS Base Score** is a score from **0 to 10** that represents the intrinsic severity of a vulnerability. A higher score indicates greater severity.

Value
0.02.55.07.510.0
Published on: 03/03/2021 00:15:12
Last modified: 10/30/2025 19:55:38
NIST: CVE source from the National Vulnerability Database (NVD)

CVSS Metrics Details

  • Base Severity: HIGH
  • Vector String: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
  • Attack Vector: LOCAL
  • Attack Complexity: LOW
  • Privileges Required: NONE
  • User Interaction: REQUIRED
  • Scope: UNCHANGED
  • Confidentiality Impact: HIGH
  • Integrity Impact: HIGH
  • Availability Impact: HIGH

FIRST Information

EPSS Score: 0.9431

The **EPSS (Exploit Prediction Scoring System)** is a score from **0 to 1** that indicates the **probability** that a vulnerability will be exploited in the real world in the next 30 days. A higher value indicates a greater likelihood of exploitation.

Value
0.00.250.50.751.0

Percentile: 0.9994

The **Percentile** indicates how much higher this vulnerability's EPSS score is compared to all other vulnerabilities in the EPSS database. For example, a percentile of 0.90 (90%) means that 90% of vulnerabilities have an EPSS score equal to or lower than the current one.

Value
0.00.250.50.751.0

*Data updated as of: 2025-11-14


CISA Information (Known Exploited Vulnerabilities)

The **CISA KEV Catalog** lists vulnerabilities that have been **actively exploited in the real world**. If a CVE is present in this catalog, it indicates that the threat is immediate and mitigation should be a top priority.

CVE **CVE-2021-27065** **IS PRESENT** in the CISA KEV Catalog!

  • Vulnerability Name: Microsoft Exchange Server Remote Code Execution Vulnerability
  • Short Description: Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.
  • Date Added to KEV: 11/03/2021
  • Vendor/Product: Microsoft / Exchange Server
  • Required Action: Apply updates per vendor instructions.
  • Due Date: 04/16/2021

Articles published on Red Hot Cyber


NVD References

Exploit PoC from GitHub

  • herwonowr/exprolog: ProxyLogon Full Exploit Chain PoC (CVE-2021–26855, CVE-2021–26857, CVE-2021–26858, CVE-2021–27065)
  • p0wershe11/ProxyLogon: ProxyLogon(CVE-2021-26855+CVE-2021-27065) Exchange Server RCE(SSRF->GetWebShell)
  • hosch3n/ProxyVulns: [ProxyLogon] CVE-2021-26855 & CVE-2021-27065 Fixed RawIdentity Bug Exploit. [ProxyOracle] CVE-2021-31195 & CVE-2021-31196 Exploit Chains. [ProxyShell] CVE-2021-34473 & CVE-2021-34523 & CVE-2021-31207 Exploit Chains.
  • evilashz/ExchangeSSRFtoRCEExploit: CVE-2021-26855 & CVE-2021-27065
  • cert-lv/exchange_webshell_detection: Detect webshells dropped on Microsoft Exchange servers exploited through "proxylogon" group of vulnerabilites (CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, CVE-2021-27065)