{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-34742", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-03-30T19:17:10.224Z", "datePublished": "2026-04-02T18:32:34.781Z", "dateUpdated": "2026-04-02T18:32:34.781Z"}, "containers": {"cna": {"title": "Model Context Protocol Go SDK: DNS Rebinding Protection Disabled by Default for Servers Running on Localhost", "problemTypes": [{"descriptions": [{"cweId": "CWE-1188", "lang": "en", "description": "CWE-1188: Insecure Default Initialization of Resource", "type": "CWE"}]}], "metrics": [{"cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "baseScore": 7.6, "baseSeverity": "HIGH", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N", "version": "4.0"}}], "references": [{"name": "https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6"}, {"name": "https://github.com/modelcontextprotocol/go-sdk/pull/760", "tags": ["x_refsource_MISC"], "url": "https://github.com/modelcontextprotocol/go-sdk/pull/760"}, {"name": "https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d", "tags": ["x_refsource_MISC"], "url": "https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d"}, {"name": "https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0", "tags": ["x_refsource_MISC"], "url": "https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0"}], "affected": [{"vendor": "modelcontextprotocol", "product": "go-sdk", "versions": [{"version": "< 1.4.0", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-04-02T18:32:34.781Z"}, "descriptions": [{"lang": "en", "value": "The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.0, the Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication with StreamableHTTPHandler or SSEHandler, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. This issue has been patched in version 1.4.0."}], "source": {"advisory": "GHSA-xw59-hvm2-8pj6", "discovery": "UNKNOWN"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.0, the Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication with StreamableHTTPHandler or SSEHandler, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. This issue has been patched in version 1.4.0."}], "id": "CVE-2026-34742", "lastModified": "2026-04-02T19:21:33.023", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 7.6, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "PASSIVE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/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", "version": "4.0", "vulnAvailabilityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-04-02T19:21:33.023", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d"}, {"source": "security-advisories@github.com", "url": "https://github.com/modelcontextprotocol/go-sdk/pull/760"}, {"source": "security-advisories@github.com", "url": "https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0"}, {"source": "security-advisories@github.com", "url": "https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-1188"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{"bugzilla": {"description": "github.com/modelcontextprotocol/go-sdk: Model Context Protocol (MCP) Go SDK: DNS rebinding vulnerability allows unauthorized access", "id": "2454608", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2454608"}, "csaw": false, "cvss3": {"cvss3_base_score": "8.0", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:N", "status": "draft"}, "cwe": "CWE-1188", "details": ["A flaw was found in the Model Context Protocol (MCP) Go SDK. When an HTTP-based MCP server is run on localhost without authentication, a malicious website can exploit a DNS rebinding vulnerability. This allows the attacker to bypass same-origin policy restrictions and send requests to the local MCP server. Consequently, an attacker could invoke tools or access resources exposed by the MCP server on behalf of the user."], "mitigation": {"lang": "en:us", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability."}, "name": "CVE-2026-34742", "package_state": [{"cpe": "cpe:/a:redhat:migration_toolkit_virtualization:2", "fix_state": "Affected", "package_name": "migration-toolkit-virtualization/mtv-cli-download-rhel9", "product_name": "Migration Toolkit for Virtualization"}, {"cpe": "cpe:/a:redhat:migration_toolkit_virtualization:2", "fix_state": "Affected", "package_name": "mtv-candidate/mtv-api-rhel9", "product_name": "Migration Toolkit for Virtualization"}, {"cpe": "cpe:/a:redhat:migration_toolkit_virtualization:2", "fix_state": "Affected", "package_name": "mtv-candidate/mtv-cli-download-rhel9", "product_name": "Migration Toolkit for Virtualization"}, {"cpe": "cpe:/a:redhat:migration_toolkit_virtualization:2", "fix_state": "Affected", "package_name": "mtv-candidate/mtv-controller-rhel9", "product_name": "Migration Toolkit for Virtualization"}, {"cpe": "cpe:/a:redhat:migration_toolkit_virtualization:2", "fix_state": "Affected", "package_name": "mtv-candidate/mtv-operator-bundle", "product_name": "Migration Toolkit for Virtualization"}, {"cpe": "cpe:/a:redhat:openshift_lightspeed", "fix_state": "Affected", "package_name": "openshift-lightspeed/openshift-mcp-server-rhel9", "product_name": "OpenShift Lightspeed"}, {"cpe": "cpe:/a:redhat:serverless:1", "fix_state": "Affected", "package_name": "openshift-serverless-1/kn-client-kn-rhel9", "product_name": "OpenShift Serverless"}, {"cpe": "cpe:/a:redhat:serverless:1", "fix_state": "Affected", "package_name": "openshift-serverless-1/kn-plugin-func-func-util-rhel9", "product_name": "OpenShift Serverless"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Affected", "package_name": "rhoai/odh-mod-arch-gen-ai-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_devspaces:3", "fix_state": "Affected", "package_name": "devspaces/udi-rhel9", "product_name": "Red Hat OpenShift Dev Spaces"}], "public_date": "2026-04-02T18:32:34Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-34742\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-34742\nhttps://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d\nhttps://github.com/modelcontextprotocol/go-sdk/pull/760\nhttps://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0\nhttps://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6"], "threat_severity": "Important"}