CVE-2026-76286 Splunk CVE debrief

Who should care

Defenders responsible for Splunk MCP Server deployments should assess exposure and verify the version of the server to prevent exploitation. This includes reviewing custom API tools and restricting access to prevent unauthorized users from running them. Additionally, defenders should monitor for suspicious activity related to custom API tools and user authentication. IT and security teams managing Splunk MCP Server should prioritize verifying the version,

Why it matters

Defenders should prioritize verifying the version of Splunk MCP Server and restricting access to custom API tools to prevent exploitation, as a Server-Side Request Forgery (SSRF) vulnerability exists in versions below 1.2.1.

• Potential unauthorized access to data and actions as a user who ran a custom API tool.
• Possible capture of user authentication tokens by an attacker controlling the URL configured for a custom API tool.
• Required verification of Splunk MCP Server version and access controls for custom API tools.

Technical summary

The vulnerability exists in Splunk MCP Server versions below 1.2.1, where a user who runs a custom API tool could have their authentication token sent to a URL configured for that tool. If another user controls that URL, they could capture the token and use it to access data and perform actions as the user who ran the tool. This requires a user with the mcp_tool_execute capability to run a custom API tool configured by another user. The vulnerability could lead to unauthorized access to sensitive data and systems. Successful exploitation requires a user who holds a role that contains the mcp_tool_execute capability to run a custom API tool configured by another user.

Defensive priority

Defenders should prioritize verifying the version of Splunk MCP Server and restricting access to custom API tools to prevent exploitation.

Recommended defensive actions

• Verify the version of Splunk MCP Server and upgrade to 1.2.1 or later if necessary.
• Restrict access to custom API tools to prevent unauthorized users from running them.
• Monitor for suspicious activity related to custom API tools and user authentication.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and source item provide details on the vulnerability, but limited information is available on potential exploitation or affected systems. The Splunk documentation provides additional context on configuring the Splunk MCP Server and managing custom tools. However, the current information does not specify the exact scope of affected systems or the extent of potential exploitation. Defenders should verify the version of Splunk MCP Server and restrict access to custom API tools to prevent exploitation.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.