{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-53937",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-06-11T15:46:12.318Z",
        "datePublished": "2026-09-08T23:21:46.554Z",
        "dateUpdated": "2026-09-14T12:09:30.392Z"
    },
    "containers": {
        "cna": {
            "title": "MCP Kotlin SDK's unbounded line buffer in StdioServerTransport/StdioClientTransport leads to memory exhaustion (DoS)",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-400",
                            "lang": "en",
                            "description": "CWE-400: Uncontrolled Resource Consumption",
                            "type": "CWE"
                        }
                    ]
                },
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-770",
                            "lang": "en",
                            "description": "CWE-770: Allocation of Resources Without Limits or Throttling",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV3_1": {
                        "attackComplexity": "LOW",
                        "attackVector": "LOCAL",
                        "availabilityImpact": "HIGH",
                        "baseScore": 6.2,
                        "baseSeverity": "MEDIUM",
                        "confidentialityImpact": "NONE",
                        "integrityImpact": "NONE",
                        "privilegesRequired": "NONE",
                        "scope": "UNCHANGED",
                        "userInteraction": "NONE",
                        "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
                        "version": "3.1"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/modelcontextprotocol/kotlin-sdk/security/advisories/GHSA-74gp-qhv5-v493",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/modelcontextprotocol/kotlin-sdk/security/advisories/GHSA-74gp-qhv5-v493"
                },
                {
                    "name": "https://github.com/modelcontextprotocol/kotlin-sdk/commit/6e6f80512fb8fcc9f3c031cfd693ccbcf9c4aaab",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/modelcontextprotocol/kotlin-sdk/commit/6e6f80512fb8fcc9f3c031cfd693ccbcf9c4aaab"
                },
                {
                    "name": "https://github.com/modelcontextprotocol/kotlin-sdk/blob/6d5bac1/kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/ReadBuffer.kt",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/modelcontextprotocol/kotlin-sdk/blob/6d5bac1/kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/ReadBuffer.kt"
                },
                {
                    "name": "https://github.com/modelcontextprotocol/kotlin-sdk/releases/tag/0.13.0",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/modelcontextprotocol/kotlin-sdk/releases/tag/0.13.0"
                }
            ],
            "affected": [
                {
                    "vendor": "modelcontextprotocol",
                    "product": "io.modelcontextprotocol:kotlin-sdk",
                    "versions": [
                        {
                            "version": "< 0.13.0",
                            "status": "affected"
                        }
                    ]
                },
                {
                    "vendor": "modelcontextprotocol",
                    "product": "io.modelcontextprotocol:kotlin-sdk-client",
                    "versions": [
                        {
                            "version": ">= 0.7.0, < 0.13.0",
                            "status": "affected"
                        }
                    ]
                },
                {
                    "vendor": "modelcontextprotocol",
                    "product": "io.modelcontextprotocol:kotlin-sdk-core",
                    "versions": [
                        {
                            "version": "< 0.13.0",
                            "status": "affected"
                        }
                    ]
                },
                {
                    "vendor": "modelcontextprotocol",
                    "product": "io.modelcontextprotocol:kotlin-sdk-server",
                    "versions": [
                        {
                            "version": ">= 0.7.0, < 0.13.0",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-09-08T23:22:04.726Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "MCP Kotlin SDK is the Kotlin Multiplatform software development kit for the Model Context Protocol. In versions 0.7.0 through 0.12.0, `ReadBuffer.append` in `kotlin-sdk-core/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/shared/ReadBuffer.kt` writes every chunk of bytes received from the stdio transport into a `kotlinx.io.Buffer` with no size cap. Frames are extracted from that buffer only when a `\\n` (0x0a) byte is observed. A peer that streams bytes without ever sending a newline causes the internal buffer to grow indefinitely until the JVM (or the surrounding host process) is OOM-killed. The leak is amplified by `StdioServerTransport` and `StdioClientTransport`, which both queue raw chunks through a `kotlinx.coroutines.channels.Channel<ByteArray>(Channel.UNLIMITED)` and then call `readBuffer.append(chunk)` without backpressure or size guard. This is a remote-pre-auth denial of service whenever an SDK stdio server's stdin is fed by an untrusted or attacker-controlled producer (for example: a host program that exec's the MCP server as a subprocess and pipes through bytes received from a network peer, or a sidecar wrapper that proxies bytes from an HTTP endpoint to the stdio transport). Version 0.13.0 fixes the issue."
                }
            ],
            "source": {
                "advisory": "GHSA-74gp-qhv5-v493",
                "discovery": "UNKNOWN"
            }
        },
        "adp": [
            {
                "references": [
                    {
                        "url": "https://github.com/modelcontextprotocol/kotlin-sdk/security/advisories/GHSA-74gp-qhv5-v493",
                        "tags": [
                            "exploit"
                        ]
                    }
                ],
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-09-14T12:09:07.813016Z",
                                "id": "CVE-2026-53937",
                                "options": [
                                    {
                                        "Exploitation": "poc"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-09-14T12:09:30.392Z"
                }
            }
        ]
    }
}