Known Exploited Vulnerability
7.8
HIGH
CVE-2021-26857
Microsoft Exchange Server Remote Code Execution Vu - [Actively Exploited]
Description

Microsoft Exchange Server Remote Code Execution Vulnerability

INFO

Published Date :

March 3, 2021, 12:15 a.m.

Last Modified :

July 25, 2024, 5:53 p.m.

Source :

[email protected]

Remotely Exploitable :

No

Impact Score :

5.9

Exploitability Score :

1.8
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

Description :

Microsoft Exchange Server contains an unspecified vulnerability that allows for remote code execution. This vulnerability is part of the ProxyLogon exploit chain.

Required Action :

Apply updates per vendor instructions.

Notes :

Reference CISA's ED 21-02 (https://www.cisa.gov/emergency-directive-21-02) for further guidance and requirements.

Public PoC/Exploit Available at Github

CVE-2021-26857 has a 30 public PoC/Exploit available at Github. Go to the Public Exploits tab to see the list.

Affected Products

The following products are affected by CVE-2021-26857 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Microsoft exchange_server
: Total Affected Vendor : 1 | Products : 1
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-26857.

URL Resource
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26857 Patch Vendor Advisory

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Profile Photo
ct-scorch/Security-Assessment-Findings-Report

Conducted a theoretical penetration test involving reconnaissance, vulnerability scanning, remediation, and documentation. Delivered a 15+ page technical report and 2-page executive summary. Utilized tools such as Nmap, Nessus, Netcat, OpenVAS, BurpSuite, and Wapiti.

Updated: 1 month, 2 weeks ago
0 stars 0 fork 0 watcher
Born at : Sept. 20, 2024, 4:13 p.m. This repo has been linked 7 different CVEs too.
Profile Photo
NaInSec/CVE-PoC-in-GitHub

All CVE - PoC in GitHub

poc proofofconcept tester allcve cvegithub cvenew cvepoc cveupdate

Updated: 2 months, 1 week ago
5 stars 2 fork 2 watcher
Born at : March 22, 2024, 3:58 p.m. This repo has been linked 928 different CVEs too.
Profile Photo
zecool/cve

None

Updated: 7 months, 3 weeks ago
1 stars 0 fork 0 watcher
Born at : March 11, 2024, 1:21 p.m. This repo has been linked 930 different CVEs too.
Profile Photo
SohelParashar/.Net-Deserialization-Cheat-Sheet

None

Updated: 6 months, 1 week ago
0 stars 0 fork 0 watcher
Born at : Feb. 27, 2024, 3:28 p.m. This repo has been linked 22 different CVEs too.
Profile Photo
BC-SECURITY/Moriarty

Moriarty is designed to enumerate missing KBs, detect various vulnerabilities, and suggest potential exploits for Privilege Escalation in Windows environments.

C#

Updated: 2 months, 1 week ago
467 stars 54 fork 54 watcher
Born at : Dec. 11, 2023, 2:15 p.m. This repo has been linked 26 different CVEs too.
Profile Photo
whoforget/CVE-POC

None

Updated: 1 year, 7 months ago
0 stars 2 fork 2 watcher
Born at : April 8, 2023, 6:19 a.m. This repo has been linked 923 different CVEs too.
Profile Photo
k0mi-tg/CVE-POC

None

Updated: 8 months, 3 weeks ago
20 stars 3 fork 3 watcher
Born at : Feb. 14, 2023, 6:10 p.m. This repo has been linked 921 different CVEs too.
Profile Photo
byinarie/Zirconium

Tool to search for IOCs related to HAFNIUM: CVE-2021-26855 CVE-2021-26857 CVE-2021-26858 CVE-2021-27065

Updated: 1 year ago
2 stars 1 fork 1 watcher
Born at : Jan. 22, 2023, 7:59 a.m. This repo has been linked 5 different CVEs too.
Profile Photo
34zY/APT-Backpack

cve-2019-11510, cve-2019-19781, cve-2020-5902,               cve-2021-1497, cve-2021-20090, cve-2021-22006, cve-2021-22205, cve-2021-26084, cve-2021-26855, cve-2021-26857, cve-2021–26857, cve-2021–26858, cve-2021–26865

Updated: 9 months, 2 weeks ago
2 stars 1 fork 1 watcher
Born at : Dec. 13, 2022, 8:41 a.m. This repo has been linked 21 different CVEs too.
Profile Photo
WhooAmii/POC_to_review

None

Updated: 8 months, 2 weeks ago
2 stars 2 fork 2 watcher
Born at : Nov. 25, 2022, 5:43 p.m. This repo has been linked 930 different CVEs too.
Profile Photo
kh4sh3i/exchange-penetration-testing

The great Microsoft exchange hack: A penetration tester’s guide (exchange penetration testing)

exchange mail pentest pentest-tool pentesting redteam exchange-server exploit zeroday

Python PowerShell C#

Updated: 1 month, 4 weeks ago
64 stars 17 fork 17 watcher
Born at : June 23, 2022, 11:21 a.m. This repo has been linked 9 different CVEs too.
Profile Photo
soosmile/POC

None

Updated: 4 months, 1 week ago
8 stars 1 fork 1 watcher
Born at : June 21, 2022, 7:45 a.m. This repo has been linked 943 different CVEs too.
Profile Photo
Ostorlab/KEV

Ostorlab KEV: One-command to detect most remotely known exploitable vulnerabilities. Sourced from CISA KEV, Google's Tsunami, Ostorlab's Asteroid and Bug Bounty programs.

cisa-kev vulnerability 0day cisa exploits

Updated: 1 month, 4 weeks ago
516 stars 32 fork 32 watcher
Born at : April 19, 2022, 8:58 a.m. This repo has been linked 1181 different CVEs too.
Profile Photo
vehemont/nvdlib

A simple wrapper for the National Vulnerability CVE/CPE API

python cve library nvd nist vulnerability python3 nvdlib wrapper api

Python

Updated: 2 months, 2 weeks ago
82 stars 26 fork 26 watcher
Born at : Oct. 15, 2021, 5:46 p.m. This repo has been linked 7 different CVEs too.
Profile Photo
bhassani/Recent-CVE

None

C

Updated: 2 years, 5 months ago
4 stars 0 fork 0 watcher
Born at : June 1, 2021, 5:04 p.m. This repo has been linked 21 different CVEs too.

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-26857 vulnerability anywhere in the article.

  • BleepingComputer
AT&T, Verizon reportedly hacked to target US govt wiretapping platform

Multiple U.S. broadband providers, including Verizon, AT&T, and Lumen Technologies, have been breached by a Chinese hacking group tracked as Salt Typhoon, the Wall Street Journal reports. The purpose ... Read more

Published Date: Oct 07, 2024 (4 weeks ago)
CVE-2021-27065 CVE-2021-26858 CVE-2021-26857 CVE-2021-26855

The following table lists the changes that have been made to the CVE-2021-26857 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Modified Analysis by [email protected]

    Jul. 25, 2024

    Action Type Old Value New Value
    Changed CPE Configuration OR *cpe:2.3:a:microsoft:exchange_server:2010:sp3:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_18:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_7:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:* OR *cpe:2.3:a:microsoft:exchange_server:2010:sp3:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_22:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2013:sp1:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_10:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_11:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_12:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_13:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_14:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_15:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_16:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_17:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_18:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_8:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_9:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:-:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_1:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_2:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_3:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_4:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_5:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_6:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_7:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:*
  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    Dec. 29, 2023

    Action Type Old Value New Value
    Changed Description Microsoft Exchange Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-26412, CVE-2021-26854, CVE-2021-26855, CVE-2021-26858, CVE-2021-27065, CVE-2021-27078. Microsoft Exchange Server Remote Code Execution Vulnerability
    Added CVSS V3.1 Microsoft Corporation AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
  • CWE Remap by [email protected]

    Jul. 12, 2022

    Action Type Old Value New Value
    Changed CWE NVD-CWE-noinfo CWE-502
  • Initial Analysis by [email protected]

    Mar. 08, 2021

    Action Type Old Value New Value
    Added CVSS V2 Metadata Victim must voluntarily interact with attack mechanism
    Added CVSS V2 NIST (AV:N/AC:M/Au:N/C:P/I:P/A:P)
    Added CVSS V3.1 NIST AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
    Changed Reference Type https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26857 No Types Assigned https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26857 Patch, Vendor Advisory
    Added CWE NIST NVD-CWE-noinfo
    Added CPE Configuration OR *cpe:2.3:a:microsoft:exchange_server:2010:sp3:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2013:cumulative_update_23:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_18:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2016:cumulative_update_19:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_7:*:*:*:*:*:* *cpe:2.3:a:microsoft:exchange_server:2019:cumulative_update_8:*:*:*:*:*:*
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-26857 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-26857 weaknesses.

Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

60.38 }} -6.75%

score

0.97848

percentile

CVSS31 - Vulnerability Scoring System
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
: