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{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:lfprojects:mcp_go_sdk:*:*:*:*:*:*:*:*", "matchCriteriaId": "92CB3EED-2D8E-4ADC-BD05-2A14C13CA7DA", "versionEndExcluding": "1.4.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "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": "2026-04-03T19:48:25.627", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.2, "source": "nvd@nist.gov", "type": "Primary"}], "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", "tags": ["Patch"], "url": "https://github.com/modelcontextprotocol/go-sdk/commit/67bd3f2e2b53ce11a16db8d976cdb8ff1e986b6d"}, {"source": "security-advisories@github.com", "tags": ["Issue Tracking", "Patch"], "url": "https://github.com/modelcontextprotocol/go-sdk/pull/760"}, {"source": "security-advisories@github.com", "tags": ["Release Notes"], "url": "https://github.com/modelcontextprotocol/go-sdk/releases/tag/v1.4.0"}, {"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/modelcontextprotocol/go-sdk/security/advisories/GHSA-xw59-hvm2-8pj6"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "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"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,1.4.0)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "go-sdk", "source": "cna", "vendor": "modelcontextprotocol"}, "product": "go-sdk", "vendor": "modelcontextprotocol"}], "analysis": {"en": {"generated_at": "2026-04-03T22:26:18.349075+00:00", "value": {"mitigation_remediation": ["Update the Model Context Protocol Go SDK to version 1.4.0 or later to enable DNS rebinding protection by default."], "summary": {"action": "Immediate Patch", "impact": "Remote code execution via DNS rebinding"}, "threat_synthesis": {"affected_systems": "All installations of the Model Context Protocol Go SDK earlier than version 1.4.0 that host an HTTP server on localhost using StreamableHTTPHandler or SSEHandler are affected. The vulnerability applies only when the server is exposed to the same machine and no authentication is required.", "description_and_impact": "The Model Context Protocol Go SDK fails to enable DNS rebinding protection by default on HTTP-based servers that run on localhost. When a local server is launched without authentication, a malicious website can perform DNS rebinding to trick the user\u2019s browser into sending requests to the local MCP server, thereby bypassing the same\u2011origin policy and allowing the attacker to invoke server tools or access data exposed by the server. This represents an information\u2011and\u2011execution\u2011type vulnerability that can provide the attacker with the same level of access as the local user.", "risk_and_exploitability": "The CVSS score of 7.6 indicates a high severity and the EPSS score of less than 1% suggests that the likelihood of exploitation is currently low, though the vulnerability is not listed in the CISA KEV catalog. An attacker would need to lure the targeted user to a malicious web page, perform a DNS rebinding attack to point a domain to the local address, and then send requests to the local MCP server. Successful exploitation would grant the attacker the same privileges as the user running the server, potentially allowing execution of arbitrary code or access to sensitive resources."}}}}, "created": "2026-04-03T07:31:43.887228+00:00", "updated": "2026-04-07T07:55:31.481011+00:00", "vendors": ["modelcontextprotocol", "modelcontextprotocol$PRODUCT$go-sdk"]}