Microsoft Office 2016 officially reached end of support on 14th October 2025, marking the end of all security updates, bug fixes, technical assistance and feature enhancements across the entire suite, including Word, Excel, PowerPoint, Outlook, Visio, Project and more.
While the software may still launch and operate, continuing to use Office 2016 in 2026 and beyond exposes organisations to escalating cybersecurity threats, compliance challenges, and operational instability [microsoft.com].
Attackers are increasingly targeting outdated systems, this means the risks of remaining on unsupported Office versions multiply quickly. Below, we explore the top security risks organisations face by not upgrading.
1. Vulnerability to new and emerging security threats
Once Office 2016 reached the end of support, Microsoft stopped issuing all security patches, meaning newly discovered vulnerabilities will remain permanently unpatched.
Even though the apps still function, they now contain security holes that cybercriminals can exploit with no possibility of remediation [microsoft.com].
Microsoft warns that continuing to use unsupported Office products can expose organisations to “serious and potentially harmful security risks,” including vulnerabilities associated with malware, spyware, and other malicious exploits. With cyberattacks becoming more sophisticated and automated, outdated software is one of the easiest entry points for threat actors. [microsoft.com]
2. Increased risk of data breaches and ransomware attacks
Cyber criminals deliberately scan the internet for devices running unsupported software versions. Without regular security updates, Office 2016 becomes an attractive target for ransomware campaigns and data theft operations.
Microsoft states that using unsupported products can negatively impact security, compliance and productivity, emphasising the increased vulnerability to attacks once security updates cease [windowsforum.com].
As ransomware groups continue to exploit known vulnerabilities for years after they are patched on supported versions, Office 2016 users fall into an ever-expanding “high‑risk zone.”
3. Lost compatibility with modern authentication and cloud security standards
As Microsoft continues to modernise cloud services and enforce stronger authentication standards, older Office clients like Office 2016 are experiencing degraded connectivity, blocked log‑ins and loss of access to cloud features. Unsupported Office versions may lose access to Microsoft 365 features entirely as newer authentication methods replace older protocols that Office 2016 can’t support.
This incompatibility does more than interrupt work, it also weakens your organisation’s identity and access security posture, making it harder to control who can access sensitive data.
4. Compliance risks and potential audit failures
Running unsupported software often violates modern security frameworks, regulatory requirements and cyber insurance criteria. Microsoft highlights that continuing to run Office 2016 can negatively impact organisational compliance, particularly because unsupported apps no longer receive critical security fixes or meet evolving standards.
For organisations bound by GDPR, Cyber Essentials, ISO 27001, PCI DSS or sector-specific regulations, non‑compliant software can result in fines, failed audits and loss of certification.
5. Exploitable integration weaknesses in the wider Microsoft ecosystem
Office 2016’s end of support coincides with the phase‑out of several other Microsoft platforms, including Windows 10 and older server products. This creates interconnected security gaps, especially when Office apps interact with unsupported Windows environments, on‑premises Exchange servers or outdated add‑ins.
The lack of interoperability updates means integration points may break – or worse, introduce new unpatched vulnerabilities that attackers can exploit laterally across systems.
6. No access to technical support or security guidance
If your organisation experiences a breach, technical issue or compatibility failure while using Office 2016, Microsoft will not provide support of any kind.
This includes no phone support, no chat assistance, and no new knowledge‑base updates. [microsoft.com]
In a security incident scenario, the lack of vendor support can significantly increase downtime, recovery costs and reputational damage.
What should you do next?
Microsoft recommends upgrading to Azure and Modern Windows 365 to remain secure and compliant. Let us take away the headache for you. Continuing to run unsupported software increases the likelihood of cyber threats, service disruptions, compliance failures and incompatibility with modern tools your organisation relies on.
Join our session on Tuesday 3rd March to learn more about how you can securely upgrade:
- Step-by-step guide on migrating from Microsoft 2016 to Azure
- Main benefits of Azure and Modern Microsoft Desktop solutions
- Key updates: what’s new and improved
- Live demo
- Upgrade path: planning your move to the Cloud
- Q&A Session
We look forward to welcoming you to our upcoming webinar where we can help support your cloud journey. Register today – or if you have any questions about compliance in the meantime, please get in touch.
