CVE-2012-3918: Cisco IOS before 15.3(1)T on Cisco 2900 devices, when a VWIC2-2MFT-T1/E1 card is configured for TDM/HDLC mo...

Security readout for executives and security teams

This is a denial-of-service issue affecting a narrow legacy Cisco IOS configuration. Certain Frame Relay traffic can cause a serial interface outage on Cisco 2900 devices using a VWIC2-2MFT-T1/E1 card in TDM/HDLC mode. Business impact depends on whether those routers still carry critical WAN circuits. Exposure is likely limited to organizations still operating Cisco 2900 routers with VWIC2-2MFT-T1/E1 cards in TDM/HDLC mode, especially where Frame Relay remains present. Modern networks without this hardware and configuration are unlikely to be affected based on the provided sources. Treat this as targeted legacy infrastructure risk. Prioritize quickly if affected routers support critical WAN, branch, voice, or provider circuits. If the organization has no Cisco 2900 Frame Relay/TDM/HDLC footprint, priority is low after inventory confirmation. Mitigation focus: Inventory Cisco 2900 routers for VWIC2-2MFT-T1/E1 cards using TDM/HDLC mode.; Identify any Frame Relay traffic crossing those serial interfaces.; Check Cisco release notes and guidance for fixed IOS 15.3(1)T or later applicability..

Prepared

Jun 14, 2026, 14:32 UTC (UTC+00:00)

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