TON Blockchain RUNVM Instruction State Pollution Vulnerability

A state pollution vulnerability exists in the TON Virtual Machine (TVM) in all versions prior to v2025.04. The issue arises in the RUNVM instruction logic, which initializes child virtual machines by transferring critical resources, such as libraries and logs, from the parent state to the child state in a non-atomic manner. If an Out-of-Gas exception occurs after the resources have been moved but before the state transition is complete, the parent VM is left with a corrupted state, rendering these resources empty or invalid. Since RUNVM allows gas isolation, the parent VM can continue executing with this corrupted state, causing unexpected behavior or denial-of-service conditions within the contract.

Impact

Exploitation of this vulnerability leads to state corruption in the parent virtual machine, causing libraries and logs to be emptied or invalidated. This corruption can disrupt normal execution and create denial-of-service conditions within the affected contract.

Remediation

Users can upgrade to TON Blockchain version v2025.04 or later, where this vulnerability has been fixed.