The vulnerability allows an attacker to submit arbitrary Python code to the /run_script endpoint without authentication. By exploiting the exposed FastAPI app object, the attacker can bypass the guarded __import__ function, import the os module, and execute operating system commands as the LMCache process. This results in full control over the host running LMCache, compromising confidentiality, integrity, and availability of the system. The CVSS score of 9.3 reflects the severity of this risk.

Vendors: LMCache; Product: LMCache; Version: v0.5.5 and all earlier releases are affected. No other versions or products are known to be impacted.

The vulnerability has a high CVSS score of 9.3 and no EPSS score is available, indicating insufficient data on current exploitation rates. It is listed as not being in the CISA KEV catalog. The attack is fully remote and unauthenticated, requiring only network access to the /run_script endpoint. Once reached, the attacker can run arbitrary code with the permissions of the LMCache service, making exploitation trivially effective if a public-facing instance is reachable.