China-nexus cyber threat groups rapidly exploit React2Shell vulnerability (CVE-2025-55182) December 29, 2025: The blog post was updated to add options for AWS Network Firewall. December 12, 2025: The blog post was updated to clarify when customers need to update their ReactJS version. Within hours of the public disclosure of CVE-2025-55182 (React2Shell) on December 3, 2025, Amazon threat intelligence teams observed active exploitation attempts by multiple China state-nexus threat groups, including Earth Lamia and Jackpot Panda. This critical vulnerability in React Server Components has a maximum Common Vulnerability Scoring System (CVSS) score of 10.0 and affects React versions 19.x and Next.js versions 15.x and 16.x when using App Router. While this vulnerability doesn’t affect AWS…