CISA added CVE-2026-76519 to its Known Exploited Vulnerabilities (KEV) catalogue on 14 October 2026. The Cisco Secure Email Gateway Relative Path Traversal Vulnerability affects Cisco Secure Email Gateway and could let an unauthenticated remote attacker write arbitrary files to the underlying operating system.
The flaw is a relative path traversal vulnerability. Its stated impact is arbitrary file writing on the affected system; the available data does not describe further consequences or the specific attack path. The vulnerability has a CVSS score of 9.8, rated Critical. Patch status is listed as unknown, and no patch or advisory URL was provided in the supplied data.
KEV inclusion indicates that active exploitation has been confirmed. The available information does not identify a specific campaign or method of exploitation. Use of the vulnerability in ransomware campaigns is unknown. CISA’s remediation deadline is 17 October 2026.
CISA requires organisations to apply mitigations in accordance with vendor instructions, ensuring compliance with BOD 26-04 guidance on prioritising security updates based on risk and CISA’s Forensics Triage Requirements. For cloud services, organisations should follow applicable BOD 26-04 guidance; if mitigations are unavailable, they should discontinue use of the product. Stakeholders must evaluate each asset’s internet exposure and ensure adherence to BOD 26-04 patching guidelines.
The requirement directly applies to federal civilian executive branch (FCEB) agencies; all organisations should review their exposure and consult Cisco’s security advisory for mitigation instructions.
For full details, consult the [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-76519) and the [CISA KEV catalogue](https://www.cisa.gov/known-exploited-vulnerabilities-catalog).