Social media is the core platform of online social networks, consisting of a large number of social actors and complex interactions between them. With the rapid development of the mobile Internet and new media technologies, various social media systems have emerged and have become indispensable for people to share information, ideas, videos, and other information in different online short-multimedia styles. By using social media systems, people are able to obtain interesting information and share their information for personal affairs or public business. Many people have grown accustomed to spending hours on social media platforms every day, demonstrating their popularity and indispensability in daily life.

The implementation process of various social media applications involves the generation and sharing of tremendous amounts of short multimedia information, including short text, images, videos, and voice clips. As a result, security-related problems also occur frequently. Social media systems are subject to cyber-attacks from malicious software and fake information. Attacks threaten users’ privacy in social media, such as personal images, identification information, and confidential data. Therefore, it is a challenging but necessary task to ensure the security of social media against malicious attacks, to protect online user privacy, and to analyze big multimodal data for auditing spreading content, personalized recommendations to users, developing new social media tools, and mining latent data value.

This Special Issue aims to collect research on security, privacy, and multimodal data analysis for social media. This Special Issue focuses on research on models of information diffusion dynamics based on spreading data analysis, algorithms of positive influence maximization and misinformation minimization based on multimodal deep learning, methods of biometric authentication based on multimodal human information, privacy protection schemes based on multimodal data analysis, personalized social media recommendation algorithms, human action recognition algorithms based on multimedia processing and multimodal fusion, and intelligent optimization algorithms for social media applications. Original research and review articles are welcome.

Potential topics include but are not limited to the following:

• Security analysis for online social networks
• Cyber-attack detection from social media information
• Information diffusion dynamics based on propagation graphs
• Fake news recognition and misinformation minimization in social media
• Information influence maximization based on graph deep learning
• Privacy protection in mobile communications
• Privacy-preserving biometrics
• Personalized recommendation based on multimodal analysis
• Multimodal data analysis and biometrics
• Multimodal data fusion for new social media analytical tools
• Evolutionary algorithms for social network optimization