Cisco warns customers of actively exploited zero-day in email gateways
Actively exploited Cisco Secure Email Gateway zero-day CVE-2026-76461 allows unauthenticated root command execution; CISA added it to KEV.
Cisco disclosed CVE-2026-76461, a zero-day in AsyncOS for Cisco Secure Email Gateway that was exploited before disclosure and lets unauthenticated remote attackers execute commands with root privileges on cloud and on-premises instances. CISA promptly added the flaw to its Known Exploited Vulnerabilities catalog, and Cisco has directly contacted cloud customers with indicators of compromise while deploying mitigations. Rapid7 and VulnCheck warn compromised gateways could enable silent email monitoring and internal pivoting from on-premises deployments.
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