Cisco Secure Email Gateway Relative Path Traversal Vulnerability

Cisco Secure Email Gateway contains a relative path traversal vulnerability that could allow an unauthenticated, remote attacker to write arbitrary files on the underlying operating system.

Why it matters

• This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, which means it has been observed being exploited in the wild.

Affected

• Vendor: Cisco
• Product: Secure Email Gateway
• Identifier: CVE-2026-76519
• FlawFind severity: high
• Weakness: CWE-23

What to do

• Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
• U.S. federal remediation deadline: 2026-10-17
• Inventory the affected product, prioritise internet-facing instances, and patch or mitigate immediately.
• Audit your own systems for the same weakness class — FlawFind can test your applications and APIs for it and prove what is exploitable.

Notes

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-afw-zqYJkjxp ; ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-76519