In Splunk MCP Server app versions earlier than 1.2.1, the credential management component deserializes stored data without validating the data type. An adversary with a Splunk admin role can provide crafted input that triggers this deserialization, enabling them to execute arbitrary commands on the underlying operating system. This flaw is an unsafe deserialization weakness classified as CWE-502.

The Splunk MCP Server app is affected. All releases below version 1.2.1 are considered vulnerable. No further sub‑version details are provided, so every build prior to 1.2.1 must be addressed.

The vulnerability carries a CVSS score of 9.1, indicating critical severity. EPSS score is not available, but the lack of public exploitation does not diminish the risk; an attacker who authenticates as a Splunk admin can trigger the flaw. The issue is not listed in the CISA KEV catalog. Compromise requires an authenticated admin session, and the attacker can run any OS command once the deserialization is triggered.