CVE-2026-76443

CVE-2026-76443 bundles multiple internally discovered improper-input-neutralization weaknesses (CWE-707 pillar) in Cisco Secure Email Gateway and Cisco Secure Email and Web Manager, found during a proactive Cisco engineering review rather than external reporting. The CVSS 9.8 vector (network, low complexity, no privileges, no user interaction) indicates the flaws can be triggered remotely by an unauthenticated attacker sending specially crafted input to the affected appliance. A successful attack yields high impact to confidentiality, integrity, and availability — consistent with prior severe issues in these products such as arbitrary file writes, OS command injection, or privilege escalation. Any organization running Cisco Secure Email Gateway or Secure Email and Web Manager without the latest hardening releases is affected. As of now there is no known public proof-of-concept, the flaw is not on CISA's KEV list, and no active exploitation has been reported.

What to do: Upgrade Cisco Secure Email Gateway and Secure Email and Web Manager to the hardened software releases specified in Cisco's advisory as soon as possible, since the flaw is unauthenticated and network-reachable. Until patched, restrict access to the management interface and web UI to trusted internal networks or VPN, and verify exposure with external port scans of your perimeter. Review logs for unexpected file writes, configuration changes, or command execution on affected appliances.