{"resultsPerPage":1,"startIndex":0,"totalResults":1,"format":"NVD_CVE","version":"2.0","timestamp":"2026-06-24T19:44:18.508","vulnerabilities":[{"cve":{"id":"CVE-2026-27896","sourceIdentifier":"security-advisories@github.com","published":"2026-02-26T01:16:25.630","lastModified":"2026-06-17T10:27:50.390","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"The Go MCP SDK used Go's standard encoding/json.Unmarshal for JSON-RPC and MCP protocol message parsing in versions prior to 1.3.1. Go's standard library performs case-insensitive matching of JSON keys to struct field tags — a field tagged json:\"method\" would also match \"Method\", \"METHOD\", etc. This violated the JSON-RPC 2.0 specification, which defines exact field names. A malicious MCP peer may have been able to send protocol messages with non-standard field casing that the SDK would silently accept. This had the potential for bypassing intermediary inspection and coss-implementation inconsistency. Go's standard JSON unmarshaling was replaced with a case-sensitive decoder in commit 7b8d81c. Users are advised to update to v1.3.1 to resolve this issue."},{"lang":"es","value":"El SDK de Go MCP utilizaba la función estándar `encoding/json.Unmarshal` de Go para el análisis de mensajes del protocolo JSON-RPC y MCP en versiones anteriores a la 1.3.1. La biblioteca estándar de Go realiza una coincidencia que no distingue entre mayúsculas y minúsculas de las claves JSON con las etiquetas de campo de las estructuras — un campo etiquetado como json:'method' también coincidiría con 'Method', 'METHOD', etc. Esto violaba la especificación JSON-RPC 2.0, que define nombres de campo exactos. Un par MCP malicioso podría haber sido capaz de enviar mensajes de protocolo con un uso de mayúsculas y minúsculas no estándar en los campos que el SDK aceptaría silenciosamente. Esto tenía el potencial de eludir la inspección intermedia y la inconsistencia entre implementaciones. El desenmascaramiento JSON estándar de Go fue reemplazado por un decodificador que distingue entre mayúsculas y minúsculas en el commit 7b8d81c. Se aconseja a los usuarios actualizar a la versión 1.3.1 para resolver este problema."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"modelcontextprotocol","product":"go-sdk","versions":[{"version":"< 1.3.1","status":"affected"}]}]}],"metrics":{"cvssMetricV40":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"4.0","vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","baseScore":7.0,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subConfidentialityImpact":"HIGH","subIntegrityImpact":"HIGH","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","confidentialityRequirement":"NOT_DEFINED","integrityRequirement":"NOT_DEFINED","availabilityRequirement":"NOT_DEFINED","modifiedAttackVector":"NOT_DEFINED","modifiedAttackComplexity":"NOT_DEFINED","modifiedAttackRequirements":"NOT_DEFINED","modifiedPrivilegesRequired":"NOT_DEFINED","modifiedUserInteraction":"NOT_DEFINED","modifiedVulnConfidentialityImpact":"NOT_DEFINED","modifiedVulnIntegrityImpact":"NOT_DEFINED","modifiedVulnAvailabilityImpact":"NOT_DEFINED","modifiedSubConfidentialityImpact":"NOT_DEFINED","modifiedSubIntegrityImpact":"NOT_DEFINED","modifiedSubAvailabilityImpact":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED"}}],"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","baseScore":7.5,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"HIGH","availabilityImpact":"NONE"},"exploitabilityScore":3.9,"impactScore":3.6}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-02-26T17:06:14.973622Z","id":"CVE-2026-27896","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-178"},{"lang":"en","value":"CWE-436"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:lfprojects:mcp_go_sdk:*:*:*:*:*:*:*:*","versionEndExcluding":"1.3.1","matchCriteriaId":"F490537C-6089-4989-A1B4-4072EADBA4DF"}]}]}],"references":[{"url":"https://github.com/modelcontextprotocol/go-sdk/commit/7b8d81c264074404abdf5aa16e2cf0c2d9c64cc0","source":"security-advisories@github.com","tags":["Patch"]},{"url":"https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-wvj2-96wp-fq3f","source":"security-advisories@github.com","tags":["Patch","Vendor Advisory"]}]}}]}