{"schema":"threatline.record/2","record":{"id":"CVE-2026-88257","aliases":["GHSA-mrg2-4747-fmpw"],"summary":"beam_mcp: nested tool argument constraints advertised but not enforced","details":"Improper Input Validation vulnerability in BeamMCP.Schema in ScriptKittyOS beam_mcp allows an MCP client to reach a tool's dispatch function with arguments that violate the input schema the server advertised. BeamMCP.Schema.validate/2 checked type, required, additionalProperties, enum and numeric bounds on the top-level arguments object only. Constraints inside nested objects and on array items (items, minItems, maxItems, minLength, maxLength, pattern, nested required, enum and additionalProperties: false) were advertised by tools/list and never checked at tools/call or prompts/get, and keywords outside the enforced subset (oneOf, anyOf, $ref) were advertised and ignored.\n\nA host whose dispatch code relies on the schema it declared receives values the schema forbids, such as an out-of-range number or an undeclared key inside a nested object. What the host does with such a value decides the impact.\n\nThis issue affects beam_mcp: from 0.1.0 before 0.10.1.","categories":["Unclassified"],"product":"beam_mcp","vendor":"ScriptKittyOS","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-88257","source_modified_at":"2026-10-08T14:09:41.540Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"beam_mcp","vendor":"ScriptKittyOS","versions":[{"lessThan":"0.10.1","status":"affected","version":"0.1.0","versionType":"semver"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-88257","source_modified_at":"2026-10-08T14:09:41.540Z","fetched_at":"2026-10-23T18:48:36.087640Z","product":"beam_mcp","vendor":"ScriptKittyOS","versions":[{"lessThan":"289dbdbad641943b29a3b8d1eb36506cc8cec10a","status":"affected","version":"083838eb8e17fe5f6fcaf761bdbe203110288b0b","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"GitHub Advisory Database","source_url":"https://github.com/ScriptKittyOS/beam_mcp/security/advisories/GHSA-mrg2-4747-fmpw","source_modified_at":"2026-10-08T13:46:05Z","fetched_at":"2026-10-23T20:37:03.234832Z","package":{"ecosystem":"erlang","name":"beam_mcp"},"range":"< 0.10.1"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-88257","source_modified_at":"2026-10-08T14:09:41.540Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"beam_mcp","ecosystem":null},"version":"0.10.1","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-88257","source_modified_at":"2026-10-08T14:09:41.540Z","fetched_at":"2026-10-23T18:48:36.087640Z","package":{"name":"beam_mcp","ecosystem":null},"version":"289dbdbad641943b29a3b8d1eb36506cc8cec10a","basis":"first unaffected version stated in the CVE record"},{"source":"GitHub Advisory Database","source_url":"https://github.com/ScriptKittyOS/beam_mcp/security/advisories/GHSA-mrg2-4747-fmpw","source_modified_at":"2026-10-08T13:46:05Z","fetched_at":"2026-10-23T20:37:03.234832Z","package":{"ecosystem":"erlang","name":"beam_mcp"},"version":"0.10.1"}],"cvss":5.3,"severity":"Medium","kev":{"listed":false},"epss":{"probability":0.00268,"percentile":0.1797,"score_date":"2026-10-23"},"published_at":"2026-10-08T13:40:55.828Z","modified_at":"2026-10-08T14:09:41.540Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-88257","fetched_at":"2026-10-23T18:48:36.087640Z","source_modified_at":"2026-10-08T14:09:41.540Z"},{"source":"GitHub Advisory Database","url":"https://github.com/ScriptKittyOS/beam_mcp/security/advisories/GHSA-mrg2-4747-fmpw","fetched_at":"2026-10-23T20:37:03.234832Z","source_modified_at":"2026-10-08T13:46:05Z"},{"source":"EPSS","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-88257","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23"}],"sources":["CVE List","GitHub Advisory Database","EPSS"],"references":[{"source":"CVE List","url":"https://github.com/ScriptKittyOS/beam_mcp/security/advisories/GHSA-mrg2-4747-fmpw","tags":["related","vendor-advisory"]},{"source":"CVE List","url":"https://cna.erlef.org/cves/CVE-2026-88257.html","tags":["related"]},{"source":"CVE List","url":"https://osv.dev/vulnerability/EEF-CVE-2026-88257","tags":["related"]},{"source":"CVE List","url":"https://github.com/ScriptKittyOS/beam_mcp/commit/083838eb8e17fe5f6fcaf761bdbe203110288b0b","tags":["related"]},{"source":"CVE List","url":"https://github.com/ScriptKittyOS/beam_mcp/commit/289dbdbad641943b29a3b8d1eb36506cc8cec10a","tags":["patch"]}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","cvss_source":"CVE List","ssvc":{"exploitation":"none","automatable":"no","technical_impact":"partial","assessed_at":"2026-10-08T13:59:14.866448Z"},"classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":null,"confidence":"unknown","reviewed":false},"change_timestamp":"2026-10-08T14:09:41.540Z","content_hash":"5401e2b92b2ae66c5c7d965b721e1b1125fb021611b0e13bd824b36e65d91e1f"}}