Cisco Adaptive Security Appliances (ASA) 5500 series devices, and the ASA Services module in Cisco Catalyst 6500 series devices, with software 7.2 before 7.2(5.3), 8.0 before 8.0(5.25), 8.1 before 8.1(2.50), 8.2 before 8.2(5.11), 8.3 before 8.3(2.23), 8.4 before 8.4(2), and 8.5 before 8.5(1.1) allow remote attackers to cause a denial of service (device reload) via crafted MSN Instant Messenger traffic, aka Bug ID CSCtl67486.
Use CWE-399, Cisco vendor hub and Adaptive Security Appliance Software product page to widen CVE-2011-3304 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2026-20103, CVE-2026-20101 and CVE-2026-20039 for nearby disclosures in the same product family. Additional editorial context is available in Cybersecurity Weekly Roundup: April 27, 2026 — Critical Zero-Days and Framework Failures.