Microsoft patched three critical vulnerabilities in Microsoft Teams during the August 2026 Patch Tuesday release, including one flaw with the maximum CVSS severity score of 10.0. For Kent SMEs relying on Teams for daily business communications, video meetings, and collaborative work, these vulnerabilities represent a significant security risk that requires immediate attention.
The timing is particularly concerning given the record-breaking volume of patches organisations must manage in 2026. With Microsoft September 2026 Patch Tuesday setting new records with 966 vulnerabilities, critical Teams flaws risk being overlooked despite their severity and the application’s central role in modern business operations.
The Three Critical Microsoft Teams Vulnerabilities Fixed in August 2026
CVE-2026-62896, CVE-2026-62918, and CVE-2026-65667 are Critical vulnerabilities affecting Microsoft Teams, with CVSS scores of 10.0 (CVE-2026-65667), 9.6 (CVE-2026-62896), and 7.5 (CVE-2026-62918)
, according to security firm CrowdStrike’s analysis of the August Patch Tuesday release.
CVE-2026-65667 and CVE-2026-62896 are elevation of privilege vulnerabilities, while CVE-2026-62918 is a spoofing vulnerability
. The maximum 10.0 CVSS score for CVE-2026-65667 places it in the most severe category possible, indicating that exploitation could allow an attacker to gain complete control over affected systems.
Elevation of privilege vulnerabilities are particularly dangerous in business environments because they allow attackers who have gained initial access—perhaps through phishing or social engineering—to escalate their permissions and move laterally across your network, accessing sensitive data and critical systems.
Microsoft Teams for Android Information Disclosure Flaw Also Patched
A separate vulnerability affecting mobile users compounds the risk for SMEs with hybrid and remote workforces.
Microsoft has released a security update for CVE-2026-65812, a vulnerability in Microsoft Teams for Android that could allow an authorized attacker to disclose sensitive information, including user credentials
.
For Kent businesses where employees routinely access Teams from mobile devices—checking messages during commutes, joining meetings from client sites, or working remotely—this vulnerability creates an additional attack vector.
Because credentials may be exposed, security teams should also review sign-in logs for suspicious access attempts, especially for accounts that use Teams on Android devices
.
Why Teams Vulnerabilities Pose Unique Risks to UK SMEs
Microsoft Teams has become mission-critical infrastructure for UK SMEs since the pandemic accelerated digital workplace adoption. Unlike vulnerabilities in rarely-used applications, Teams flaws directly threaten:
- Business continuity: Teams downtime or compromise disrupts customer communications, internal collaboration, and daily operations
- Sensitive data exposure: Teams stores and transmits confidential client information, financial data, and strategic discussions
- Supply chain risk: External Teams channels connect your organisation to clients and suppliers, creating potential lateral movement paths for attackers
- Compliance obligations: For firms subject to GDPR, Teams security directly impacts data protection compliance and breach notification requirements
The external communication feature that makes Teams valuable for business also introduces risk.
Microsoft Teams allows users to communicate with other Teams users, even if they are not in the same organization. This is done by default, without any additional configuration required
, according to security researchers at ThreatLocker.
What Kent SMEs Must Do This Week to Protect Teams Deployments
1. Deploy August 2026 Teams Updates Immediately
Microsoft has released patches for all three critical vulnerabilities through the August 2026 Patch Tuesday release. For organisations using Microsoft 365 with automatic updates enabled, Teams typically updates itself. However, SMEs should verify patch deployment rather than assume it:
- Check the Teams version number in Settings → About → Version
- Force a manual update check if automatic updates are delayed
- Confirm updates across all devices, including employee personal devices used for business Teams access
- Pay particular attention to Android mobile devices, which require separate patching for CVE-2026-65812
With Microsoft now recommending deploying Windows updates within 3 days, the same urgency applies to critical Teams vulnerabilities given their maximum severity scores.
2. Review Teams External Access Configuration
The default Teams configuration that permits external communication increases your attack surface. While this functionality supports legitimate business needs, it should be configured deliberately rather than left at default settings:
- Audit which external domains your organisation regularly communicates with via Teams
- Consider implementing an allowlist of approved external domains rather than permitting all external access
- Review whether
you should use Microsoft Teams Admin Center and disable the ability to communicate with Teams users whose accounts aren’t managed by your organization - Document the business justification for external Teams access to support informed risk decisions
3. Check Sign-In Logs for Suspicious Activity
Given the credential exposure risk from the Android vulnerability, SMEs should proactively review authentication logs for unusual patterns that might indicate exploitation attempts or successful compromises:
- Unusual sign-in locations or times for Teams-enabled accounts
- Multiple failed authentication attempts followed by successful sign-ins
- Access from unexpected device types or operating systems
- Privilege escalation activities following Teams-related authentication
This log review is particularly important for organisations that have been slower to deploy the August patches, as the window of vulnerability exposure increases exploitation risk.
4. Communicate Patching Status to Cyber Insurance Providers
For Kent SMEs with cyber insurance policies, unpatched critical vulnerabilities in core business applications like Teams may affect coverage. Cyber insurance renewal requirements in 2026 increasingly demand specific technical controls, and demonstrating timely patch management for maximum-severity flaws supports both coverage maintenance and claims processes should an incident occur.
The Broader Context: Record Patch Volumes Challenge SME Security
These Teams vulnerabilities arrive during an unprecedented period of patch volume.
Microsoft has addressed 415 vulnerabilities in its August 2026 security update release
, and the September release that followed was even larger.
For resource-constrained SMEs, the challenge isn’t simply applying individual patches—it’s maintaining security posture when the volume of required updates exceeds available IT capacity. This is precisely why AI-powered vulnerability discovery is driving record patch volumes in 2026, creating a security dilemma for organisations without dedicated security teams.
Critical vulnerabilities in mission-critical applications like Teams must rise to the top of triage queues precisely because exploitation would have immediate, visible impact on business operations—not just theoretical security consequences.
Get Expert Support for Teams Security and Patch Management
Kent SMEs struggling to keep pace with critical security updates while maintaining daily business operations don’t need to choose between security and productivity. Meridian Micro Limited provides comprehensive IT support services covering patch management, security monitoring, and Microsoft 365 optimisation for businesses across Kent and the South East.
Our team stays current with the latest security releases, triages vulnerabilities based on your specific risk profile, and ensures critical patches like these Teams updates are deployed promptly without disrupting your operations. We’ll also review your Teams configuration to balance external collaboration needs with security requirements appropriate for your business.
Contact Meridian Micro today on 01303 883111 to discuss how we can help protect your Teams deployment and manage the increasing complexity of business IT security in 2026.