Kaspersky Security Bulletin reviews what shaped telecom cybersecurity in 2025 and what is likely to persist in 2026. Advanced Persistent Threat (APT) activity, supply-chain compromise, DDoS disruption and SIM-enabled fraud continued to pressure operators in 2025, while newer technology deployments introduce additional operational risk. In 2025, telecom operators faced broad threat categories. Targeted intrusions (APTs) continued to focus on gaining stealthy access to operator environments for long-term espionage and leverage through privileged network positioning. Supply chain vulnerabilities remained an entry point: telecom ecosystems rely on many vendors, contractors and tightly ...