Stay updated on DoS threats. Explore the latest news and insights on Denial of Service attacks, prevention tips, and cybersecurity strategies.
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Background for this topic.
Denial of service (DoS) is an attack that makes a system, network, or application unavailable by exhausting resources or triggering failure. Floods can consume bandwidth, connection state, CPU, memory, or request-processing capacity; a software defect may instead be exploited to crash a service. A distributed denial-of-service (DDoS) attack generates traffic from many systems, increasing volume and complicating source-based blocking. The material security impact is loss of availability for users and dependent services, including websites, APIs, DNS, and operational systems.
Mitigation should match the bottleneck. Rate limits, request validation, connection protections, caching, and service isolation can reduce application and state-exhaustion attacks; volumetric traffic generally needs filtering or absorption upstream of the network. Monitoring should distinguish abnormal request patterns from ordinary load and alert on saturation, while tested failover, traffic diversion, and restoration procedures limit outage duration. Vulnerability management and timely patching reduce DoS caused by remotely triggerable crashes, but do not replace capacity planning and resilience testing.
Cisco warned this week that two vulnerabilities, which have been exploited in zero-day attacks, are now being abused to force ASA and FTD firewalls into reboot loops. [...]
Cisco on Wednesday disclosed that it became aware of a new attack variant that's designed to target devices running Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software releases that are susceptible to CVE-2025-20333 and CVE-2025-20362
ENISA report reveals DDoS accounted for 60% of public sector security incidents last year