{"id":78022,"date":"2026-02-26T04:17:46","date_gmt":"2026-02-26T00:47:46","guid":{"rendered":"https:\/\/afaghhosting.net\/blog\/cve-2026-27896-mcp-go-sdk-vulnerable-to-improper-handling-of-case-sensitivity\/"},"modified":"2026-02-26T04:17:46","modified_gmt":"2026-02-26T00:47:46","slug":"cve-2026-27896-mcp-go-sdk-vulnerable-to-improper-handling-of-case-sensitivity","status":"publish","type":"post","link":"https:\/\/afaghhosting.net\/blog\/cve-2026-27896-mcp-go-sdk-vulnerable-to-improper-handling-of-case-sensitivity\/","title":{"rendered":"CVE-2026-27896 &#8211; MCP Go SDK Vulnerable to Improper Handling of Case Sensitivity"},"content":{"rendered":"<p>CVE ID : CVE-2026-27896<\/p>\n<p>Published :  Feb. 26, 2026, 12:47 a.m. | 21\u00a0minutes ago<\/p>\n<p>Description : The Go MCP SDK used Go&#8217;s standard encoding\/json.Unmarshal for JSON-RPC and MCP protocol message parsing in versions prior to 1.3.1. Go&#8217;s standard library performs case-insensitive matching of JSON keys to struct field tags \u2014 a field tagged json:&#8221;method&#8221; would also match &#8220;Method&#8221;, &#8220;METHOD&#8221;, 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&#8217;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.<\/p>\n<p>Severity: 0.0 | NA<\/p>\n<p>Visit the link for more details, such as CVSS details, affected products, timeline, and more&#8230;\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"<p>CVE ID : CVE-2026-27896 Published : Feb. 26, 2026, 12:47 a.m. | 21\u00a0minutes ago Description : The Go MCP SDK used Go&#8217;s standard encoding\/json.Unmarshal for JSON-RPC and MCP protocol message parsing in versions prior to 1.3.1. Go&#8217;s standard library performs case-insensitive matching of JSON keys to struct field tags \u2014 a field tagged json:&#8221;method&#8221; would &hellip;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[],"class_list":["post-78022","post","type-post","status-publish","format-standard","hentry","category-vulnerability"],"_links":{"self":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/78022","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/comments?post=78022"}],"version-history":[{"count":0,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/posts\/78022\/revisions"}],"wp:attachment":[{"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/media?parent=78022"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/categories?post=78022"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/afaghhosting.net\/blog\/wp-json\/wp\/v2\/tags?post=78022"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}