CVE-2026-27896High· 7.0▾ TwilightThe 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 tagg…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 38.5 · likelihood 0.1 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Sep 16.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
Last analysed / modified upstream
0.3%
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.
go-sdk < 1.3.1Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-64684Medium· 6.8RMCP is an official Rust SDK for the Model Context Protocol
CVE-2026-63128High· 7.5RMCP is an official Rust SDK for the Model Context Protocol
CVE-2026-63127High· 8.2RMCP is an official Rust SDK for the Model Context Protocol
CVE-2026-53937Medium· 6.2MCP Kotlin SDK is the Kotlin Multiplatform software development kit for the Model Context Protocol
CVE-2026-40453Critical· 9.9The fix for CVE-2025-27636 added setLowerCase(true) to HttpHeaderFilterStrategy so that case-variant header names such as 'CAmelExecCommandExecutable' are filtered out alongside 'CamelExecCommandExecutable'
CVE-2026-73553High· 7.5Envoy is an open source edge and service proxy designed for cloud-native applications