Top 10 Most Exploited Vulnerabilities in 2026 – A Guide for Canadian and Quebec SMEs
Introduction
“We apply updates once a month, that’s enough.”
This sentence, heard every week at Sécurité Info Services, is now outdated, dangerous, and potentially fatal for your business.
In 2026, the exploitation window for a critical vulnerability is measured in hours, sometimes even minutes. Cybercriminal bots constantly scan the Internet for known flaws. If your system is not patched, it will be found—and exploited.
Key stats for Canadian SMEs
- 83% of Canadian SMEs feel confident about their cybersecurity
- 46% experienced at least one incident in the past 12 months
- 12% experienced multiple incidents
- Main causes:
- Phishing: 21%
- Weak passwords: 20%
- Lack of monitoring: 20%
- Unpatched vulnerabilities remain a major attack vector
Why this guide is different
We selected only vulnerabilities that:
- Affect software widely used by SMEs
- Are actively exploited (based on the CISA KEV – 2026 catalog)
- Can be quickly fixed, even with limited resources
Methodology
Sources used:
- CISA – Known Exploited Vulnerabilities catalog
- Alerts from the RCMP and the Canadian Centre for Cyber Security
- Field data from Sécurité Info Services
Selection criteria:
- Added to KEV between January and April 2026
- Present in 90% of SMEs
- Score CVSS ≥ 7.0
- Confirmed real-world exploitation
Top 10 exploited vulnerabilities in 2026
🥇 #1 – CVE-2026-24858
FortiOS – FortiCloud SSO Authentication Bypass
CVSS: 9.8 | Critical
Affected products: FortiOS 7.0.x to 7.6.x (< 7.6.6)
Description:
Complete authentication bypass via FortiCloud SSO. Attackers can create admin accounts and extract configurations.
Status: Actively exploited since January 2026.
Fixes:
- Upgrade to FortiOS 7.6.6
- Disable FortiCloud SSO if upgrade is not possible
- Check for suspicious admin accounts (“backup”, “support”)
⚠️ Warning: the update removes the SSL VPN Tunnel.
🥈 #2 – CVE-2026-24285
Windows Win32kfull – Privilege Escalation
CVSS: 7.0 | High
Impact: Elevation to SYSTEM level from limited access.
Fixes:
- Apply Microsoft update from March 10, 2026
- Enable automatic Windows Update
🥉 #3 – CVE-2026-20045
Cisco Unified Communications Manager – RCE
CVSS: 8.2 | High
Impact: Remote command execution without authentication.
Fixes:
- Apply Cisco patch from April 21, 2026
- Isolate management interface
- Review access logs
#4 – CVE-2026-35616
FortiClient EMS – Authentication Bypass
CVSS: 9.8 | Critical
Impact: Full control of client machines.
Fixes:
- Apply April 2026 hotfix
- Block EMS access from the Internet
#5 – CVE-2026-21533
Windows RDS – Privilege Escalation
CVSS: 7.8 | High
Fixes:
- Apply update KB5034803 (February 2026)
- Ensure consistent patching across all RDS roles
#6 – CVE-2026-33826
Active Directory – RCE
CVSS: 8.0 | High
Status: ❌ Patch pending
Temporary measures:
- Restrict network access to domain controllers
- Enhance AD logging (4662, 4769, 4776)
#7 – CVE-2026-24286
Langflow – Code Injection
CVSS: 9.8 | Critical
Fixes:
- Update Langflow
- Never expose the interface publicly
#8 – CVE-2026-33827
Microsoft SharePoint – Deserialization
CVSS: 8.8 | High
Fixes:
- Apply Microsoft patch (March 2026)
- Audit SharePoint logs
#9 – CVE-2026-24860
Trivy – CI/CD Supply Chain
CVSS: 9.4 | Critical
Fixes:
- Update Trivy
- Revoke and regenerate all exposed secrets
#10 – CVE-2026-24287
n8n – Code Injection
CVSS: 9.9 | Critical
Fixes:
- Apply patch
- Restrict access to internal network or VPN
Quick summary
| # | CVE | Product | CVSS | Status |
|---|---|---|---|---|
| 1 | 24858 | FortiOS | 9.8 | ✅ |
| 2 | 24285 | Windows | 7.0 | ✅ |
| 3 | 20045 | Cisco UC | 8.2 | ✅ |
| 4 | 35616 | FortiClient EMS | 9.8 | ✅ |
| 5 | 21533 | Windows RDS | 7.8 | ✅ |
| 6 | 33826 | Active Directory | 8.0 | ❌ |
| 7 | 24286 | Langflow | 9.8 | ✅ |
| 8 | 33827 | SharePoint | 8.8 | ✅ |
| 9 | 24860 | Trivy | 9.4 | ✅ |
| 10 | 24287 | n8n | 9.9 | ✅ |
Conclusion
Your SME is not immune, but it can effectively protect itself with:
- Organization-wide MFA
- Patching within 14 days
- Immutable 3-2-1 backups
- Anti-phishing training
Need help?
Sécurité Info Services supports SMEs with:
- Vulnerability audits
- Prioritized remediation plans
- Outsourced patch management
- Continuous CISA KEV monitoring
📞 Free 30-minute assessment