CVE-2026-40007: Apache IoTDB: Unauthenticated unbounded recursion in IoTDB AirGap receiver's E-language prefix parser causes per-connection StackOverflowError

Uncontrolled Recursion, Uncontrolled Resource Consumption vulnerability in Apache IoTDB. When pipe_air_gap_receiver_enabled=true, the IoTDB AirGap receiver's readLength method calls itself recursively each time it recognises the E-language prefix in socket data, with no depth limit. An unauthenticated attacker can send a stream of repeated E-language prefixes that drives the recursion arbitrarily deep, exhausting the receiver thread's JVM stack and raising StackOverflowError. This issue affects Apache IoTDB: from 1.0.0 before 2.0.10. Users are recommended to upgrade to version 2.0.10, which fixes the issue.