{"answers":{"affected":"","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53937 exists.","fix":"No fix has been published for CVE-2026-53937 yet. Limit exposure of the affected software until one is available.","what":"CVE-2026-53937 is a medium-severity denial of service vulnerability in io.modelcontextprotocol:kotlin-sdk, published on 8 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-53937 and fix it if it is affected.\n\nWhat it is: CVE-2026-53937 is a medium-severity denial of service vulnerability in io.modelcontextprotocol:kotlin-sdk, published on 8 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-53937 exists.\n\nAffected product: io.modelcontextprotocol:kotlin-sdk. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-53937/ (Markdown: https://insights.sbomify.com/CVE-2026-53937/index.md)","id":"CVE-2026-53937","markdown":"https://insights.sbomify.com/CVE-2026-53937/index.md","name":"CVE-2026-53937","record":{"aliases":["GHSA-74gp-qhv5-v493"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"MCP Kotlin SDK","requires_auth":"none","summary":"An attacker can cause memory exhaustion and crash the application by sending data without newlines to the MCP Kotlin SDK stdio transport.","user_interaction":"not_required","vuln_class":"denial_of_service"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[],"cvss":{"score":6.2,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-770","name":"Allocation of Resources Without Limits or Throttling"},{"id":"CWE-400","name":"Uncontrolled Resource Consumption"}],"description":"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\u003cByteArray\u003e(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.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":false,"headline":"MCP Kotlin SDK's unbounded line buffer in StdioServerTransport/StdioClientTransport leads to memory exhaustion (DoS)","id":"CVE-2026-53937","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"denial_of_service","year":"2026"},"n_packages":0,"n_references":4,"next":{"headline":"OpenIDC/cjose has a heap buffer overflow in AES Key Wrap decryption (A128KW/A192KW/A256KW)","id":"CVE-2026-53938"},"packages":[],"prev":{"headline":"CiliumLocalRedirectPolicy addressMatcher allows cross-namespace service traffic hijacking and can break service translation","id":"CVE-2026-53935"},"products":["io.modelcontextprotocol:kotlin-sdk","io.modelcontextprotocol:kotlin-sdk-client","io.modelcontextprotocol:kotlin-sdk-core","io.modelcontextprotocol:kotlin-sdk-server"],"published":"2026-09-08","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-09-14","vendors":["modelcontextprotocol"]},"summary":"An attacker can cause memory exhaustion and crash the application by sending data without newlines to the MCP Kotlin SDK stdio transport.","url":"https://insights.sbomify.com/CVE-2026-53937/"}