CVE-2026-27896
7.5 · HIGHOverview
CVE-2026-27896 is a high-severity vulnerability affecting lfprojects mcp_go_sdk. It was published on February 26, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
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.
Remediation
Check the references section for vendor advisories and patches from lfprojects. Update mcp_go_sdk to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| lfprojects | mcp_go_sdk | >= 0, < 1.3.1 | Affected |
References
Frequently Asked Questions
What is CVE-2026-27896?
CVE-2026-27896 is a high-severity vulnerability affecting lfprojects mcp_go_sdk. It was published on February 26, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-27896?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-27896?
Check the references section for vendor advisories and patches from lfprojects. Update mcp_go_sdk to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-27896?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-27896 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
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