CVE Alert: CVE-2025-55321 – Microsoft – Azure Monitor

Risk verdict

High risk: an authenticated, high-privilege attacker could exploit a cross-site scripting flaw in Azure Monitor Log Analytics to spoof the UI, with serious potential impacts on data integrity and confidentiality.

Why this matters

Spoofed monitoring pages could mislead operators, hide tampering, or enable data exfiltration from logs and alerts. For regulated environments, this undermines trust in telemetry, hampers incident response, and could violate compliance requirements if monitoring data is manipulated.

Most likely attack path

Given AV:N, AC:L, PR:H, UI:N and S:C, exploitation requires a high-privilege, authenticated user. An insider or compromised admin could inject a payload via the web UI, enabling spoofing across the monitoring surface and potential access to sensitive log data or alert configurations. Lateral movement is plausible only if broader admin access exists; otherwise impact remains confined to the monitored scope with potential cascading effects on related workloads.

Who is most exposed

Organisations relying on Azure Monitor Log Analytics with elevated administrative roles are most at risk. Multi-tenant deployments or managed service providers handling client telemetry could see exposure broaden beyond a single workspace.

Detection ideas

• Unusual UI changes or DOM anomalies in Log Analytics pages
• Alerts of elevated XSS attempts targeting the Azure Monitor endpoints
• Abnormal session activity or token usage by privileged accounts
• Unexpected modifications to monitoring configurations or dashboards

Mitigation and prioritisation

• Apply the official Microsoft patch from MSRC immediately; verify coverage across affected tenants/workspaces.
• Enforce input sanitisation server-side, plus a strong Content Security Policy and proper XSS protections (script-src, CSP nonce).
• Restrict admin access to the monitor surfaces; review and rotate credentials; enable MFA; increase auditing of privileged activity.
• Schedule patching and testing in a controlled window; validate telemetry integrity afterwards.
• If available, enable WAF rules or anomaly detection specific to UI spoofing events.