Full Report
Multiple vulnerabilities have been discovered in Cisco Secure Email products, the most severe of which could allow for remote code execution.Cisco Secure Email Gateway (formerly ESA) is an email security appliance that filters spam, malware, and other threats at the mail gateway.Cisco Secure Email and Web Manager (formerly SMA) is a centralized management and reporting platform for Cisco Secure Email Gateway and Secure Web Appliance deployments. Successful exploitation of the most severe of these vulnerabilities could allow for remote code execution as root, which may lead to the complete compromise of the affected device.
Analysis Summary
# Vulnerability: Multiple Flaws in Cisco Secure Email Products
## CVE Details
- **CVE ID:** CVE-2026-76440 (Primary RCE focus), CVE-2026-76441, CVE-2026-76442, CVE-2026-76443, CVE-2026-76461
- **CVSS Score:** 9.8 (Critical - Estimated for primary RCE)
- **CWE:** CWE-78 (OS Command Injection), CWE-20 (Improper Input Validation)
## Affected Systems
- **Products:**
- Cisco Secure Email Gateway (formerly Email Security Appliance - ESA)
- Cisco Secure Email and Web Manager (formerly Security Management Appliance - SMA)
- **Versions:** Multiple versions are affected. Users should check specific release trains (e.g., 14.x, 15.x) against the vendor advisory.
- **Configurations:** Systems with web-based management interfaces or specific content filtering features enabled.
## Vulnerability Description
The most critical flaw involves an OS command injection vulnerability in the web-based management interface. This occurs because the application fails to properly validate user-supplied input that is subsequently used in system-level commands. An attacker can send crafted HTTP requests to the affected device to execute arbitrary commands. Other identified vulnerabilities include improper hardening and input validation flaws that could facilitate unauthorized access or information disclosure.
## Exploitation
- **Status:** Not exploited (No reports of active exploitation in the wild at the time of advisory release).
- **Complexity:** Low
- **Attack Vector:** Network (Remote)
## Impact
- **Confidentiality:** High (Full access to email logs, configurations, and sensitive data)
- **Integrity:** High (Ability to modify system files and filtering rules)
- **Availability:** High (Potential for total device lockout or bricking)
- **Note:** Successful exploitation can lead to root-level privileges, resulting in complete compromise.
## Remediation
### Patches
Cisco has released software updates to address these vulnerabilities. It is recommended to migrate to the following fixed releases or later:
- **Secure Email Gateway:** Refer to Cisco Advisory `cisco-sa-esa-inj-2bLVGmhX` for specific version mapping.
- **Secure Email and Web Manager:** Update to the latest maintenance release provided by Cisco TAC or the software download center.
### Workarounds
- **Access Control Lists (ACLs):** Restrict access to the management interface (HTTPS) to only trusted internal networks and hosts.
- **Disable Unused Services:** Turn off any management services or ports that are not strictly required for operation.
## Detection
- **Indicators of Compromise:**
- Unusual administrative user creation in system logs.
- Unexpected outbound network connections from the management IP of the appliance.
- Presence of non-standard files in `/tmp` or other writable directories (requires shell access/forensics).
- **Detection Methods:**
- Monitor web server logs for suspicious characters in HTTP POST/GET requests (e.g., `;`, `&`, `|`, `$()`).
- Use Cisco's `show version` and `show history` commands to audit recent changes.
## References
- **Vendor Advisories:**
- hxxps[://]sec[.]cloudapps[.]cisco[.]com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-inj-2bLVGmhX
- hxxps[://]sec[.]cloudapps[.]cisco[.]com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-esa-dfCrfXkm
- **CVE Records:**
- hxxps[://]www[.]cve[.]org/CVERecord?id=CVE-2026-76440
- hxxps[://]www[.]cve[.]org/CVERecord?id=CVE-2026-76441
- hxxps[://]www[.]cve[.]org/CVERecord?id=CVE-2026-76442
- hxxps[://]www[.]cve[.]org/CVERecord?id=CVE-2026-76443
- hxxps[://]www[.]cve[.]org/CVERecord?id=CVE-2026-76461