Vulnerability intelligence
CVE-2026-76440 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
To assist customers in patching and streamline the disclosure process, Cisco has grouped these issues by their underlying vulnerability class - Common Weakness Enumeration (CWE) - and assigned a single Common Vulnerabilities and Exposures identifier (CVE ID) to each CWE grouping.
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Secure Email Gateway and Cisco Secure Email and Web Manager engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities.
The vulnerabilities tracked by CVE-2026-76440 are related to path traversal issues that are grouped under the Common Weakness Enumeration (CWE) Pillar CWE-23.
Source: NVD
Cisco Security Advisories · Updated Oct 14, 2026
These vulnerabilities affect Cisco Secure Email Gateway and Cisco Secure Email and Web Manager, regardless of device configuration.
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
There are no workarounds that address these vulnerabilities.
To remediate these vulnerabilities and avoid future exposure as described in this advisory, Cisco strongly recommends that customers upgrade to the fixed software indicated in this advisory.
In the following tables, the left column lists Cisco software releases. The right column indicates whether a release is affected by the vulnerabilities that are described in this advisory and the first release that includes the fix for these vulnerabilities. Customers are advised to upgrade to an appropriate fixed software release as indicated in this section.
Cisco Secure Email Gateway Release | First Fixed Release |
|---|---|
15.5 and earlier | 15.5.5-014 |
16.0 | Migrate to a fixed release. |
16.5 | 16.5.0-780 |
Cisco Secure Email and Web Manager Release | First Fixed Release |
|---|---|
15.5 and earlier | 15.5.5-006 |
16.0 | Migrate to a fixed release. |
16.5 | 16.5.0-429 |
The software can be upgraded over the network by using the System Upgrade options in the web-based management interface of the appliance.
To upgrade a device by using the web-based management interface, do the following:
Choose System Administration > System Upgrade.
Click Upgrade Options.
Click Download and Install.
Choose a release to upgrade to.
In the Upgrade Preparation area, choose the appropriate options.
Click Proceed to begin the upgrade. A progress bar displays the status of the upgrade.
After the upgrade is complete, the device reboots.
To upgrade a device by using the CLI, do the following:
Run upgrade.
Enter DOWNLOADINSTALL.
Choose a release to upgrade to.
Choose the appropriate options throughout the upgrade process.
After the upgrade is complete, the device reboots.
Cisco Secure Email Cloud includes Cisco Secure Email Gateway and Cisco Secure Email and Web Manager devices as part of the service solution. Cisco provides regular maintenance of the products included in this solution. Customers can also request a software upgrade by contacting Cisco Secure Email Cloud support.
The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.
Except as otherwise noted previously, the Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities that are described in this advisory.