{"data":{"id":"09342252-ade4-485a-8ce4-8b6de9bbc3ec","title":"GHSA-xw59-hvm2-8pj6: DNS Rebinding Protection Disabled by Default in Model Context Protocol Go SDK for Servers Running on Localhost","summary":"The Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. A malicious website could use DNS rebinding to bypass same-origin restrictions and send requests to an HTTP-based MCP server running on localhost without authentication, using `StreamableHTTPHandler` or `SSEHandler`. This could let an attacker invoke tools or access resources on the user's behalf, and servers using stdio transport are not affected.","solution":"Fixed in 1.4.0: servers created via `StreamableHTTPHandler` or `SSEHandler` now have DNS rebinding protection enabled by default when binding to `localhost`. Users are advised to update to version 1.4.0.","labels":["security"],"sourceUrl":"https://github.com/advisories/GHSA-xw59-hvm2-8pj6","publishedAt":"2026-04-01T21:09:09.000Z","cveId":"CVE-2026-34742","cweIds":["CWE-1188"],"cvssScore":"8.1","cvssSeverity":"high","severity":"high","attackType":["other"],"issueType":"vulnerability","affectedPackages":["github.com/modelcontextprotocol/go-sdk@< 1.4.0 (fixed: 1.4.0)"],"affectedPackageNames":["github.com/modelcontextprotocol/go-sdk"],"affectedVendors":[],"affectedVendorsRaw":["Model Context Protocol (MCP) Go SDK"],"classifierModel":"claude-haiku-5-5","classifierPromptVersion":"v4","summaryPromptVersion":"v2","headline":null,"headlinePromptVersion":null,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N","attackVector":"network","attackComplexity":"low","privilegesRequired":"none","userInteraction":"required","exploitMaturity":"unknown","epssScore":0.00664,"epssCheckedAt":"2026-10-10T04:57:23.399Z","kevDateAdded":null,"advisoryAliases":["GHSA-xw59-hvm2-8pj6"],"affectedPackagesSource":null,"affectedPackagesCheckedAt":null,"patchAvailable":true,"disclosureDate":"2026-04-01T21:09:09.000Z","capecIds":null,"crossRefCount":0,"attackSophistication":"moderate","impactType":["confidentiality","integrity"],"aiComponentTargeted":"plugin","llmSpecific":false,"classifierConfidence":0.9,"researchCategory":null,"atlasIds":null}}