Cisco patches exploited Secure Email Gateway zero

Feeds.4Sysops •IT News • October 14, 2026

Cisco has patched CVE-2026-76519, a zero-day in Secure Email Gateway (SEG) that attackers are exploiting to gain root-level command execution. The flaw can be triggered remotely without authentication by sending a specially crafted email attachment through a vulnerable appliance. Source

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Critical Cisco Secure Email Gateway Vulnerability Exploited Cisco has disclosed a critical vulnerability in its Secure Email Gateway (SEG), tracked as CVE-2026-76519, which allows unauthenticated remote attackers to execute commands with root privileges. This flaw arises from improper handling of email attachments when the File Reputation service is enabled. Active exploitation of this vulnerability has been confirmed, with attackers able to send crafted emails that compromise the system without user interaction. The vulnerability affects both physical and virtual appliances running vulnerable versions of Cisco AsyncOS, specifically those with Content Scanner Tools versions earlier than 25.3.0.5525. Cisco released patches on October 14, 2026, and has advised affected organizations to apply these updates immediately. The CVSS score for this vulnerability is 9.8, indicating a critical severity level. Organizations are urged to review their configurations to determine if they are at risk. 14 sources 78

Extracted Entities

Cisco patches exploited Secure Email Gateway zero

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Extracted Entities

Attack Types (1)

CVEs (1)

MITRE ATT&CK (1)

Platforms (1)