CVE-2026-108714
MCP Kotlin SDK through 0.15.0 Memory Exhaustion via Application.mcpWebSocket
- State
- Published
- Severity
- 8.7 High
- Published
- Oct 11, 2026
- Updated
- Oct 14, 2026
- Reserved
- Oct 11, 2026
Description
MCP Kotlin SDK through 0.15.0 contains an uncontrolled memory allocation vulnerability that allows remote clients to exhaust server memory because Application.mcpWebSocket installs Ktor WebSockets without a maxFrameSize limit. Attackers can send small frame headers declaring payloads near 2 GiB over one or a few connections, forcing huge heap allocations and causing denial of service.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.7 High | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | VulnCheck |
Weaknesses
- CWE-770 Allocation of Resources Without Limits or Throttling
Affected Products
| Product | Versions |
|---|---|
kotlin-sdkmodelcontextprotocol |
|
References
- https://hackmd.io/@haind/mcp-kotlin-sdk-websocket-frame-allocation-dosthird-party-advisory
- https://github.com/modelcontextprotocol/kotlin-sdk/blob/0.15.0/kotlin-sdk-server/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/WebSocketMcpKtorServerExtensions.kt#L41-L63technical-description
- https://github.com/modelcontextprotocol/kotlin-sdk/blob/0.15.0/kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/WebSocketMcpTransport.kt#L60-L85technical-description
- https://github.com/modelcontextprotocol/kotlin-sdkproduct
- VulnCheck Advisory: MCP Kotlin SDK through 0.15.0 Memory Exhaustion via Application.mcpWebSocketthird-party-advisory
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