High severity · published Oct 11, 2026
CVE-2026-108714
MCP Kotlin SDK through 0.15.0 Memory Exhaustion via Application.mcpWebSocket
7.5
CVSS
0.4%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 29% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KO
kotlin-sdk · modelcontextprotocol
through 0.15.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-108714
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-108714
third-party-advisory
https://hackmd.io/@haind/mcp-kotlin-sdk-websocket-frame-allocation-dos
technical-description
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
technical-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-L85
product
https://github.com/modelcontextprotocol/kotlin-sdk
third-party-advisory
https://www.vulncheck.com/advisories/mcp-kotlin-sdk-through-0.15.0-memory-exhaustion-via-application-mcpwebsocket