CVE-2014-3347: Cisco IOS 15.1(4)M2 on Cisco 1800 ISR devices, when the ISDN Basic Rate Interface is enabled, allows remote...

Security readout for executives and security teams

This issue can make a specific Cisco 1800 ISR router hang when ISDN Basic Rate Interface is enabled. An attacker needs the ISDN phone number, so exposure is narrower than internet-wide scanning. Business impact is service interruption for sites still relying on these legacy routers or ISDN circuits. Most likely exposure is legacy Cisco 1800 ISR deployments with active ISDN BRI lines. Organizations without Cisco 1800 ISR, IOS 15.1(4)M2, or enabled ISDN BRI are not indicated as affected by the provided sources. Treat as targeted availability risk for legacy branch connectivity, not a broad enterprise compromise issue. Prioritize if affected routers support critical sites, emergency communications, or high-availability network paths. Mitigation focus: Inventory Cisco 1800 ISR routers and confirm IOS versions.; Identify whether ISDN Basic Rate Interface is enabled and still required.; Check Cisco advisory CSCul77897 for fixed software or workarounds..

Prepared

Jun 14, 2026, 07:14 UTC (UTC+00:00)

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