CVE-2026-108714 modelcontextprotocol CVE debrief

Who should care

Defenders responsible for Kotlin SDK deployments, particularly those using versions up to 0.15.0, should assess exposure and prioritize verification and potential upgrades. They should review server configurations to ensure adequate memory allocation and limit exposure to denial of service. Additionally, defenders should monitor server performance and memory usage for signs of potential exploitation and verify the version of MCP Kotlin SDK in use.

Why it matters

CVE-2026-108714 is a high-severity vulnerability in MCP Kotlin SDK through 0.15.0 that allows remote clients to cause denial of service by exhausting server memory. Defenders should prioritize verifying and upgrading to a fixed version.

• Denial of service due to memory exhaustion
• Potential disruption to service availability
• Need for verification of affected versions and exposure
• Priority on upgrading to a fixed version of MCP Kotlin SDK

Technical summary

The MCP Kotlin SDK through 0.15.0 contains an uncontrolled memory allocation vulnerability in Application.mcpWebSocket, which allows remote clients to exhaust server memory, leading to denial of service. The vulnerability is caused by the lack of a maxFrameSize limit in Ktor WebSockets. This can be exploited by sending small frame headers declaring payloads near 2 GiB over one or a few connections, forcing huge heap allocations. Defenders should prioritize verifying and upgrading to a fixed version of MCP Kotlin SDK, as the vulnerability allows remote clients to exhaust server memory, leading to denial of service. The CVE record and source item provide details on the vulnerability, including its description, CV

Defensive priority

Defenders should prioritize verifying and upgrading to a fixed version of MCP Kotlin SDK, as the vulnerability allows remote clients to exhaust server memory, leading to denial of service.

Recommended defensive actions

• Verify the version of MCP Kotlin SDK in use and upgrade to a fixed version if necessary
• Review server configurations to ensure adequate memory allocation and limit exposure to denial of service
• Monitor server performance and memory usage for signs of potential exploitation
• 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
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance

Evidence notes

The CVE record and source item provide details on the vulnerability, including its description, CVSS score, and affected versions. However, the corpus does not establish versions beyond 0.15.0, exploitation, impact, or remediation, which require verification from the supplied official sources.

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.