CVE-2026-76440

CVE-2026-76440 groups multiple path traversal weaknesses (CWE Pillar CWE-23) found during Cisco's internal security review of Cisco Secure Email Gateway and Cisco Secure Email and Web Manager, addressed via software hardening releases. With a CVSS 3.1 base score of 9.8 (network vector, low attack complexity, no privileges, no user interaction), a remote unauthenticated attacker could craft requests that escape intended directory boundaries to read, modify, or delete files on the appliance, potentially leading to full confidentiality, integrity, and availability impact. Any organization running an affected version of these email perimeter appliances is exposed, particularly since these gateways are designed to be internet-facing. No public proof-of-concept exists, the flaw is not in the CISA Known Exploited Vulnerabilities catalog, and no exploitation has been reported to date. Because the bugs were internally discovered, technical detail is limited and defenders should prioritize patching rather than await exploit intelligence.

What to do: Apply the software hardening release identified in Cisco's advisory for both Cisco Secure Email Gateway and Cisco Secure Email and Web Manager as soon as maintenance windows allow, given the unauthenticated 9.8 rating. Restrict the web management interface to trusted admin networks or VPN so only SMTP ports are exposed to the internet. Review appliance logs for unexpected file access, anomalous admin activity, or unfamiliar file modifications that could indicate prior probing.