CVE-2026-20057 is a vulnerability in Cisco Cyber Vision's Snort 3 Detection Engine related to the Visual Basic for Applications (VBA) feature. The root cause is a divide-by-zero error triggered by insufficient error checking when decompressing VBA data. Specifically, when the Snort 3 engine processes crafted VBA data packets, it may encounter a divide-by-zero condition that causes the detection engine to crash unexpectedly. This crash leads to the engine restarting, which disrupts normal monitoring and detection capabilities, effectively causing a denial of service (DoS) condition. The vulnerability affects a wide range of Cisco Cyber Vision versions from 3.0.0 through 5.3.1, indicating a long-standing issue across multiple releases. Exploitation requires no authentication or user interaction and can be performed remotely by sending maliciously crafted VBA data to the affected detection engine. Although the vulnerability does not compromise confidentiality or integrity, the availability impact can be significant, especially in environments relying on continuous network monitoring for security and operational awareness. No public exploits have been reported yet, but the broad version impact and ease of exploitation make timely remediation critical. Cisco has not yet published patches, so organizations should monitor for updates and consider temporary mitigations such as network segmentation and traffic filtering to limit exposure.

The primary impact of CVE-2026-20057 is a denial of service condition caused by the Snort 3 Detection Engine crashing and restarting. This disrupts the continuous monitoring and detection capabilities of Cisco Cyber Vision, potentially leaving industrial and critical infrastructure networks blind to threats during the downtime. Organizations relying on Cisco Cyber Vision for real-time visibility into operational technology (OT) environments may experience reduced situational awareness, increasing the risk of undetected attacks or operational failures. While confidentiality and integrity remain unaffected, the loss of availability can have cascading effects, particularly in sectors such as manufacturing, energy, utilities, and transportation where Cisco Cyber Vision is commonly deployed. The ease of remote exploitation without authentication or user interaction increases the risk of automated attacks or scanning by threat actors. Although no known exploits exist currently, the vulnerability’s presence across many versions and the critical role of the affected product in network security elevate the potential impact globally.

1. Monitor Cisco’s official advisories closely and apply patches immediately once they become available to address the divide-by-zero error in the Snort 3 Detection Engine. 2. Until patches are released, implement network segmentation to isolate Cisco Cyber Vision devices from untrusted networks, reducing exposure to crafted VBA data packets. 3. Deploy strict ingress filtering and deep packet inspection on network segments hosting Cisco Cyber Vision to detect and block malformed VBA data or suspicious traffic patterns targeting the Snort 3 engine. 4. Consider temporarily disabling or restricting the VBA feature within Snort 3 if feasible, to prevent processing of potentially malicious VBA data. 5. Maintain comprehensive monitoring and alerting on Cisco Cyber Vision system health to detect unexpected restarts or crashes promptly. 6. Conduct regular backups of configuration and monitoring data to enable rapid recovery in case of service disruption. 7. Engage with Cisco support for guidance on interim mitigations and best practices tailored to your deployment environment. 8. Educate security teams about this vulnerability to ensure rapid incident response if exploitation attempts are detected.