CVE-2001-0867: Cisco 12000 with IOS 12.0 and line cards based on Engine 2 does not properly filter does not properly filte...

Security readout for executives and security teams

This old Cisco router flaw could let fragmented network traffic bypass access control lists on specific Cisco 12000 deployments. For executives, the concern is not a broad modern software emergency, but whether legacy core routing equipment still relies on affected ACL behavior for network segmentation or filtering. Exposure appears limited to organizations still operating Cisco 12000 Series Internet Routers with IOS 12.0 and Engine 2-based line cards. Risk is higher where ACL fragment filtering is part of perimeter, backbone, or segmentation enforcement. Treat as a legacy infrastructure risk. It deserves prompt inventory validation, especially in regulated or segmented environments, but the provided evidence does not support an active-exploitation emergency. Mitigation focus: Identify any Cisco 12000 routers still in production or disaster recovery networks.; Confirm IOS 12.0 use and whether line cards are Engine 2-based.; Review Cisco advisory GSR-ACL-pub.shtml for vendor remediation guidance..

Prepared

Jul 1, 2026, 07:46 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.