Windows Admin Center flaws exposed hybrid Azure and on-prem environments to takeover
Researchers disclosed multiple vulnerabilities in Microsoft Windows Admin Center (WAC) that could let attackers compromise hybrid environments spanning Azure and on-premises infrastructure. Cymulate said one exploit chain enabled unauthenticated, one-click remote code execution when a victim visited a malicious URL, combining response-based cross-site scripting, insecure redirect handling, and insecure credential storage to steal credentials, run arbitrary PowerShell commands, and capture Azure tokens. The issues affected both Azure-integrated and on-prem deployments, with the most severe risk falling on self-managed on-prem WAC instances that could be used to execute commands on managed servers and pivot into cloud resources.
Additional flaws presented at Black Hat Asia were tracked as CVE-2025-64669, CVE-2026-20965, CVE-2026-23660, and CVE-2026-32196, including a non-write-protected on-prem WAC directory and weaknesses in proof-of-possession token validation that could allow token reuse or forgery and takeover of tenant VMs. Microsoft said Azure-managed instances received server-side fixes after responsible disclosure, and the company has patched the broader set of vulnerabilities with no evidence of active exploitation. Researchers urged organizations to update on-prem WAC immediately, remove outdated exposed instances, and treat both cloud and on-prem management planes as tier-zero assets because WAC can serve as a bidirectional path between the two environments.
Timeline
Apr 23, 2026
Cymulate publicly discloses WAC exploit chain and hybrid-cloud risks
At Black Hat Asia, Cymulate researchers publicly disclosed the Windows Admin Center vulnerabilities and described how they could enable one-click unauthenticated RCE, credential theft, token abuse, and movement between on-premises and Azure environments. They warned that on-premises deployments were especially exposed and urged organizations to update and verify no outdated instances remained accessible.
Apr 23, 2026
Microsoft patches four Windows Admin Center vulnerabilities
Microsoft patched four vulnerabilities affecting Windows Admin Center in hybrid Azure and on-premises environments, including CVE-2025-64669, CVE-2026-20965, CVE-2026-23660, and CVE-2026-32196. Reporting states there was no indication of active exploitation at the time of disclosure.
Aug 22, 2025
Microsoft applies server-side fixes to Azure-managed WAC instances
After the responsible disclosure, Microsoft deployed server-side mitigations for Azure-managed Windows Admin Center instances, automatically protecting cloud customers. The fixes addressed the Azure side of the disclosed attack chain.
Aug 22, 2025
Cymulate responsibly discloses Windows Admin Center flaws to Microsoft
Cymulate Research Labs reported a critical Windows Admin Center vulnerability chain to Microsoft under responsible disclosure. The disclosure date is explicitly given as August 22, 2025.
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