Multiple Privilege‑Escalation Vulnerabilities in Microsoft Edge (CVE‑2026‑91708‑91729)

On 21 September 2026, the CERT‑FR CSIRT released an alert describing 22 separate CVEs in Microsoft Edge that can be exploited to gain elevated privileges and trigger an unspecified security failure.

What happened

Each CVE (CVE‑2026‑91708 through CVE‑2026‑91729) targets a distinct component of Edge, allowing local or remote code execution with higher privileges. The vulnerabilities are present in the version released on 21 September 2026.

Impact

• Privilege escalation on the affected host.
• Potential for full system compromise if exploited.
• No known exploitation in the wild yet, but the severity warrants immediate action.

Mitigation

• Upgrade Microsoft Edge to the latest patched release (≥ 22 Sep 2026).
• If upgrade is not possible, disable Edge or restrict its execution via group policy.
• Apply the vendor‑issued security updates for the affected components.

Detection & Monitoring

• Watch for anomalous privilege‑elevation events in Windows Event Logs (Event ID 4670, 4672).
• Use endpoint detection to flag execution of Edge binaries with elevated privileges.
• Cross‑reference CVE IDs in threat‑intel feeds for indicators of compromise.