---
title: "SECURITY ALERT: Microsoft On-Premises Exchange Server Vulnerability for April 2021"
description: Systems Engineering's Security Alert offers guidance on the CVE 2021 28481 security update which affects Exchange servers 2013, 2016, and 2019.
image: https://blog.systemsengineering.com/hubfs/286x143-Security%20Alert_Systems%20Engineering.png
---

[![header-logo](https://blog.systemsengineering.com/hs-fs/hubfs/header-logo.png?width=138&name=header-logo.png)](https://www.systemsengineering.com)

888.624.6737

<https://www.linkedin.com/company/systemsengineering-><https://www.facebook.com/systemsengineeringinc>

![Spyglass](https://www.systemsengineering.com/wp-content/uploads/search-google-e1751908066340.png)

- [Careers](https://www.systemsengineering.com/about/careers/)
- [Blog](https://blog.systemsengineering.com/blog)
- [Events](https://www.systemsengineering.com/news-resources/events/)
- [Case Studies](https://www.systemsengineering.com/case-studies/)
- [Client Center](https://www.systemsengineering.com/client-center/)
- [CONTACT](https://www.systemsengineering.com/about/contact/)

- IT Services 
    - [Managed IT](https://www.systemsengineering.com/managed-it/) 
          - [IT Essentials](https://www.systemsengineering.com/managed-it/it-essentials/)
          - [Microsoft Services](https://www.systemsengineering.com/managed-it/microsoft-services/)
          - [Modern Workplace](https://www.systemsengineering.com/managed-it/modern-desktop/)
          - [Help Desk](https://www.systemsengineering.com/managed-it/help-desk/)
          - [Network Assessment](https://www.systemsengineering.com/managed-it/network-assessment/)
    - [IT Consulting Services](https://www.systemsengineering.com/it-consulting-services/) 
          - [Compliance](https://www.systemsengineering.com/compliance)
          - [IT Policies-as-a-Service](https://www.systemsengineering.com/it-consulting-services/it-policies-as-a-service/)
          - [Virtual CIO](https://www.systemsengineering.com/it-consulting-services/virtual-cio/)
          - [Engineering Services](https://www.systemsengineering.com/it-consulting-services/engineering-services/)
          - [Project Management](https://www.systemsengineering.com/it-consulting-services/project-management/)
          - [Business Continuity](https://www.systemsengineering.com/it-consulting-services/business-continuity/)
          - [Assessments & Gap Analyses](https://www.systemsengineering.com/it-consulting-services/get-it-assessed/)
    - [Software Services](https://www.systemsengineering.com/software-services/) 
          - [Application Development](https://www.systemsengineering.com/software-services/application-development/)
          - [SharePoint](https://www.systemsengineering.com/software-services/sharepoint/)
          - [Database Services](https://www.systemsengineering.com/software-services/database-services/)
- [IT Security](https://www.systemsengineering.com/security/) 
    - [Adaptive Cybersecurity Framework (aCSF)](https://www.systemsengineering.com/se-adaptive-cybersecurity-framework-acsf/)
    - [Cloud Security](https://www.systemsengineering.com/security/cloud-security/) 
          - [Cloud Security Resources](https://www.systemsengineering.com/security/cloud-security/cloud-security-resources/)
    - [Security Awareness Training](https://www.systemsengineering.com/security/security-awareness-training/)
    - [Cybersecurity Risk Assessment](https://www.systemsengineering.com/security/cybersecurity-risk-assessment/)
- [Compliance](https://www.systemsengineering.com/compliance/) 
    - [Cybersecurity Maturity Model Certification (CMMC)](https://www.systemsengineering.com/compliance/cmmc-compliance/) 
          - [CMMC Compliance Service](https://www.systemsengineering.com/compliance/cmmc-compliance/cmmc-compliance-service/)
          - [CMMC Resources](https://www.systemsengineering.com/compliance/cmmc-compliance/cmmc-resources/)
    - [National Credit Union Administration (NCUA)](https://www.systemsengineering.com/compliance/ncua/)
- [Cloud Services](https://www.systemsengineering.com/cloud-services/) 
    - [Cloud Management](https://www.systemsengineering.com/cloud-services/cloud-management/)
    - [Cloud Security](https://www.systemsengineering.com/security/cloud-security/)
    - [Office 365 Migration & Support](https://www.systemsengineering.com/cloud-services/office-365-migration-support/) 
          - [Office 365 Backup](https://www.systemsengineering.com/cloud-services/office-365-migration-support/office-365-backup/)
    - [Cloud Assessment](https://www.systemsengineering.com/cloud-services/cloud-assessment/)
- [Industries](https://www.systemsengineering.com/industries/) 
    - [Construction](https://www.systemsengineering.com/industries/construction/)
    - [Education](https://www.systemsengineering.com/industries/education/)
    - [Financial Services](https://www.systemsengineering.com/industries/financial-services/) 
          - [Accountants & Wealth Managers](https://www.systemsengineering.com/industries/financial-services/accountants-wealth-managers/)
          - [Banks](https://www.systemsengineering.com/industries/financial-services/banks/)
          - [Credit Unions](https://www.systemsengineering.com/industries/financial-services/credit-unions/)
    - [Government](https://www.systemsengineering.com/industries/government/)
    - [Healthcare](https://www.systemsengineering.com/industries/healthcare/)
    - [Law Firms](https://www.systemsengineering.com/industries/legal/)
    - [Manufacturers](https://www.systemsengineering.com/industries/manufacturer/)
    - [Nonprofit](https://www.systemsengineering.com/industries/nonprofits/)
- [About](https://www.systemsengineering.com/about/) 
    - [Leadership](https://www.systemsengineering.com/about/leadership/)
    - [Our Difference](https://www.systemsengineering.com/about/our-difference/)
    - [Our Partners](https://www.systemsengineering.com/about/our-partners/)
    - [Culture](https://www.systemsengineering.com/culture/)
    - [Contact](https://www.systemsengineering.com/about/contact/)

- Managed IT 
    - [Overview](https://www.systemsengineering.com/managed-it/)
    - [IT Essentials](https://www.systemsengineering.com/managed-it/it-essentials/)
    - [Microsoft Services](https://www.systemsengineering.com/managed-it/microsoft-services/)
    - [Modern Workplace](https://www.systemsengineering.com/managed-it/modern-workplace/)
    - [Help Desk](https://www.systemsengineering.com/managed-it/help-desk/)
    - [Network Assesment](https://www.systemsengineering.com/managed-it/network-assessment/)
- IT Consulting Services 
    - [Overview](https://www.systemsengineering.com/it-consulting-services/)
    - [Virtual CIO](https://www.systemsengineering.com/it-consulting-services/virtual-cio/)
    - [CMMC Compliance](https://www.systemsengineering.com/compliance/cmmc-compliance/)
    - [IT Policies-as-a-Service](https://www.systemsengineering.com/it-consulting-services/it-policies-as-a-service/)
    - [Engineering Services](https://www.systemsengineering.com/it-consulting-services/engineering-services/)
    - [Project Management](https://www.systemsengineering.com/it-consulting-services/project-management/)
    - [Business Continuity](https://www.systemsengineering.com/it-consulting-services/business-continuity/)
    - [Assessments & Gap Analyses](https://www.systemsengineering.com/it-consulting-services/get-it-assessed/)
- Software Services 
    - [Overview](https://www.systemsengineering.com/software-services/)
    - [Application Development](https://www.systemsengineering.com/software-services/application-development/)
    - [SharePoint](https://www.systemsengineering.com/software-services/sharepoint/)
    - [Database Services](https://www.systemsengineering.com/software-services/database-services/)
- IT Security 
    - [Overview](https://www.systemsengineering.com/security/)
    - [Adaptive Cybersecurity Framework (aCSF)](https://www.systemsengineering.com/se-adaptive-cybersecurity-framework-acsf/)
    - Cloud Security 
          - [Service Overview](https://www.systemsengineering.com/security/cloud-security/)
          - [Cloud Security Resources](https://www.systemsengineering.com/security/cloud-security/cloud-security-resources/)
    - [Security Awareness Training](https://www.systemsengineering.com/security/security-awareness-training/)
    - [Cybersecurity Risk Assesment](https://www.systemsengineering.com/security/cybersecurity-risk-assessment/)
- Compliance 
    - [Overview](https://www.systemsengineering.com/compliance/)
    - [Cybersecurity Maturity Model Certification (CMMC)](https://www.systemsengineering.com/compliance/cmmc-compliance/) 
          - [CMMC Compliance Service](https://www.systemsengineering.com/compliance/cmmc-compliance/cmmc-compliance-service/)
          - [CMMC Gap Analysis](https://www.systemsengineering.com/compliance/cmmc-compliance/cmmc-gap-analysis/)
          - [CMMC Resources Hub](https://www.systemsengineering.com/compliance/cmmc-compliance/cmmc-resources/)
    - [National Credit Union Administration (NCUA)](https://www.systemsengineering.com/compliance/ncua/)
- Cloud Services 
    - [Overview](https://www.systemsengineering.com/cloud-services/)
    - [Cloud Management](https://www.systemsengineering.com/cloud-services/cloud-management/)
    - [Cloud Security](https://www.systemsengineering.com/cloud-services/cloud-migration/)
    - Office 365 
          - [Office 365 Migration & Support](https://www.systemsengineering.com/cloud-services/office-365-migration-support/)
          - [Office 365 Backup](https://www.systemsengineering.com/cloud-services/office-365-migration-support/office-365-backup/)
    - [Cloud Assessment](https://www.systemsengineering.com/cloud-services/cloud-assessment/)
- Industries 
    - [Overview](https://www.systemsengineering.com/industries/)
    - [Construction](https://www.systemsengineering.com/industries/construction/)
    - [Education](https://www.systemsengineering.com/industries/education/)
    - [Financial Services](https://www.systemsengineering.com/industries/financial-services/) 
          - [Banks](https://www.systemsengineering.com/industries/financial-services/banks/)
          - [Credit Unions](https://www.systemsengineering.com/industries/financial-services/credit-unions/)
          - [Accountants & Wealth Managers](https://www.systemsengineering.com/industries/financial-services/accountants-wealth-managers/)
    - [Government](https://www.systemsengineering.com/industries/government/)
    - [Healthcare](https://www.systemsengineering.com/industries/healthcare/)
    - [Legal](https://www.systemsengineering.com/industries/legal/)
    - [Manufacturers](https://www.systemsengineering.com/industries/manufacturers/)
    - [Nonprofits](https://www.systemsengineering.com/industries/nonprofits/)
- About 
    - [Overview](https://www.systemsengineering.com/about/)
    - [Leadership](https://www.systemsengineering.com/about/leadership/)
    - [Our Difference](https://www.systemsengineering.com/about/our-difference/)
    - [Employee-Owned](https://www.systemsengineering.com/about/esop/)
    - [Our Partners](https://www.systemsengineering.com/about/our-partners/)
    - Careers & Internships 
          - [Openings](https://www.systemsengineering.com/about/careers/)
          - [Benefits](https://www.systemsengineering.com/about/careers/benefits/)
          - [Internships](https://www.systemsengineering.com/about/careers/internships/)
    - [Culture](https://www.systemsengineering.com/culture/)
- [Case Studies](https://www.systemsengineering.com/case-studies/)
- [Blog](https://blog.systemsengineering.com/blog)
- [Events](https://www.systemsengineering.com/events/)
- [Client Center](https://www.systemsengineering.com/client-center/)
- [Contact](https://www.systemsengineering.com/about/contact/)

888.624.6737

[Email Us](mailto:info@systemsengineering.com)

![syse-blog-header](https://blog.systemsengineering.com/hs-fs/hubfs/Logos/syse-blog-header.jpg?width=1440&name=syse-blog-header.jpg "syse-blog-header")

# SECURITY ALERT: Microsoft On-Premises Exchange Server Vulnerability for April 2021

[![Share on facebook](https://blog.systemsengineering.com/hs-fs/hubfs/facebook-color.png?width=60&name=facebook-color.png)](http://www.facebook.com/share.php?u=https://blog.systemsengineering.com/blog/security-alert-microsoft-on-premises-exchange-server-vulnerability-for-april-2021&utm_medium=social&utm_source=facebook) [![Share on linkedin](https://blog.systemsengineering.com/hs-fs/hubfs/linkedin-color.png?width=60&name=linkedin-color.png)](http://www.linkedin.com/shareArticle?mini=true&url=https://blog.systemsengineering.com/blog/security-alert-microsoft-on-premises-exchange-server-vulnerability-for-april-2021&utm_medium=social&utm_source=linkedin) [![Share on email](https://blog.systemsengineering.com/hs-fs/hubfs/email-color.png?width=60&name=email-color.png)](mailto:?subject=Check%20out%20https://blog.systemsengineering.com/blog/security-alert-microsoft-on-premises-exchange-server-vulnerability-for-april-2021&utm_medium=social&utm_source=email%20&body=Check%20out%20https://blog.systemsengineering.com/blog/security-alert-microsoft-on-premises-exchange-server-vulnerability-for-april-2021&utm_medium=social&utm_source=email) 

 April 15, 2021 | Posted in:

[Security Bulletins & Alerts](https://blog.systemsengineering.com/blog/topic/security-bulletins-alerts)

Posted by [Systems Engineering](https://blog.systemsengineering.com/blog/author/systems-engineering)

On April 13, Microsoft released its monthly patches for vulnerabilities found within their products. In their release announcement, Microsoft strongly recommends prioritizing the CVE 2021 28481 security update which affects Exchange servers 2013, 2016, and 2019. This vulnerability allows hackers access to mailboxes to read or even exfiltrate sensitive information.

Microsoft stated, "We have not seen the vulnerability used in attacks against our customers. However, given recent adversary focus on Exchange, we recommend customers install the updates as soon as possible to ensure they remain protected from these and other threats. Customers using Exchange Online are already protected and do not need to take any action. More information on installing these updates is available in our [Exchange Release blog](https://techcommunity.microsoft.com/t5/exchange-team-blog/released-april-2021-exchange-server-security-updates/ba-p/2254617)."

This vulnerability is separate from the[Zero Day Exchange vulnerabilities](https://blog.systemsengineering.com/blog/security-alert-microsoft-on-premises-exchange-server-vulnerability) we reported in March.

### Course of Action

Following Microsoft's recommendations, Systems Engineering applied the critical security updates to our managed patching clients who have affected on-premises Exchange servers.

For our clients who do not subscribe to a Systems Engineering patching service and have an affected on-premises Exchange server, we recommend applying [the security update](https://techcommunity.microsoft.com/t5/exchange-team-blog/released-april-2021-exchange-server-security-updates/ba-p/2254617) as soon as possible.

If you have questions about this security alert, please reach out to your Account Manager.

### Join the Conversation!

### Posts by Category

- [IT Solutions & Support (70)](https://blog.systemsengineering.com/blog/topic/it-solutions-support)
- [Announcements (64)](https://blog.systemsengineering.com/blog/topic/announcements)
- [Security Bulletins & Alerts (59)](https://blog.systemsengineering.com/blog/topic/security-bulletins-alerts)
- [Cybersecurity (55)](https://blog.systemsengineering.com/blog/topic/cybersecurity)
- [Business Transformation (30)](https://blog.systemsengineering.com/blog/topic/business-transformation)
- [Cloud Security (27)](https://blog.systemsengineering.com/blog/topic/cloud-security)
- [Workforce Enablement (21)](https://blog.systemsengineering.com/blog/topic/workforce-enablement)
- [Compliance (17)](https://blog.systemsengineering.com/blog/topic/compliance)
- [Network Security (13)](https://blog.systemsengineering.com/blog/topic/network-security)
- [Artificial Intelligence (10)](https://blog.systemsengineering.com/blog/topic/artificial-intelligence)

### Follow Us On Social

<https://www.linkedin.com/company/systemsengineering-> <https://twitter.com/sysengineering> <https://www.facebook.com/systemsengineeringinc>

### Contact Us

[888.624.6737](tel:888.624.6737)  
[info@systemsengineering.com](mailto:info@systemsengineering.com)

### Connect With Us

<https://www.linkedin.com/company/systemsengineering-> <https://www.facebook.com/systemsengineeringinc>

### Receive Our Blog

- [IT Services](https://www.systemsengineering.com/)
- [IT Security](https://www.systemsengineering.com/security/)
- [Compliance](https://www.systemsengineering.com/compliance/)
- [Cloud Services](https://www.systemsengineering.com/cloud-services/)
- [Industries](https://www.systemsengineering.com/industries/)
- [About](https://www.systemsengineering.com/about/)

- [Careers](https://www.systemsengineering.com/about/careers/)
- [White Papers](https://www.systemsengineering.com/white-papers/)
- [Case Studies](https://www.systemsengineering.com/case-studies/)
- [Blog](https://blog.systemsengineering.com/blog)
- [Events](https://www.systemsengineering.com/news-resources/events/)
- [Client Center](https://www.systemsengineering.com/client-center/)

![Ft-logo](https://blog.systemsengineering.com/hs-fs/hubfs/Ft-logo.png?width=105&name=Ft-logo.png)

 

 

888.624.6737 | [info@systemsengineering.com](mailto:info@systemsengineering.com)

Copyright 2025 Systems Engineering. All Rights Reserved. [Privacy Policy](https://www.systemsengineering.com/privacy-policy) [Support](https://www.systemsengineering.com/support/) [Trust Center](https://systems.app.ctrlmap.com/tp/trust/portal/links?puid=8010ba57-5a2e-40b4-9c56-2c18873c9e5f&trustPortalId=MQ==&code=4642)