CVE-2026-108714

HIGH 7.5

MCP Kotlin SDK through 0.15.0 Memory Exhaustion via Application.mcpWebSocket

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-770
Vendor	modelcontextprotocol
Product	kotlin-sdk
Published	Oct 11, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

modelcontextprotocol / kotlin-sdk

0 ≤ 0.15.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

hackmd.io: https://hackmd.io/@haind/mcp-kotlin-sdk-websocket-frame-allocation-dos github.com: https://github.com/modelcontextprotocol/kotlin-sdk/blob/0.15.0/kotlin-sdk-server/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/server/WebSocketMcpKtorServerExtensions.kt#L41-L63 github.com: https://github.com/modelcontextprotocol/kotlin-sdk/blob/0.15.0/kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/WebSocketMcpTransport.kt#L60-L85 github.com: https://github.com/modelcontextprotocol/kotlin-sdk vulncheck.com: https://www.vulncheck.com/advisories/mcp-kotlin-sdk-through-0.15.0-memory-exhaustion-via-application-mcpwebsocket

Credits

HaiND from the Post and Telecommunication Institute of Technology