A critical authentication bypass vulnerability (CVE-2025-49752) has been disclosed in Microsoft Azure Bastion. The flaw allows remote attackers to bypass authentication mechanisms and escalate privileges to administrative levels, potentially granting full control over connected virtual machines.
Business Impact
This is a severe cloud infrastructure risk. Azure Bastion is a hardened gateway for secure RDP/SSH access. Compromising it effectively gives attackers the “keys to the castle,” allowing them to pivot laterally across the cloud environment, deploy ransomware, or exfiltrate sensitive data from backend servers.
Why It Happened
The vulnerability stems from a flaw in how Azure Bastion validates session tokens, allowing an attacker to replay or forge credentials to bypass security checks. Microsoft has released emergency guidance and patches.
Recommended Executive Action
Treat this as an immediate emergency. Direct cloud security teams to verify that Microsoft’s automatic updates have applied to your Azure Bastion instances. Rotate all SSH keys and administrative credentials for VMs accessed via Bastion as a precaution.
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