The vulnerability stems from using Oj.load() instead of Oj.strict_load() for deserialization. The commit 5267b45 shows replacements of load() with strict_load() across multiple files handling message processing. Oj.load() permits deserialization of arbitrary Ruby objects, enabling RCE through crafted payloads. Each identified function directly processes untrusted input using unsafe deserialization, making them clear exploitation points. The CWE-502 mapping and the nature of the fixes confirm these as vulnerable points.