{"id":"CVE-2026-4270","state":"PUBLISHED","title":"AWS API MCP File Access Restriction Bypass","description":"Improper Protection of Alternate Path exists in the no-access and workdir feature of the AWS API MCP Server versions >= 0.2.14 and < 1.3.9 on all platforms may allow the bypass of intended file access restriction and expose arbitrary local file contents in the MCP client application context.\n\nTo remediate this issue, users should upgrade to version 1.3.9.","publishedAt":"2026-03-16T16:07:53.324Z","updatedAt":"2026-03-16T18:17:17.927Z","severity":{"score":6.8,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","source":"AMZN"},"assigner":"AMZN","products":["AWS AWS API MCP Server"],"affected":[{"vendor":"AWS","product":"AWS API MCP Server","defaultStatus":"unaffected","versions":[{"version":"0.2.14","status":"affected","lessThan":"1.3.9","versionType":"custom"}]}],"references":["https://aws.amazon.com/security/security-bulletins/2026-007-AWS/","https://pypi.org/project/awslabs.aws-api-mcp-server/1.3.9/"],"weaknesses":["CWE-424"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/4xxx/CVE-2026-4270.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-4270","state":"PUBLISHED","datePublished":"2026-03-16T16:07:53.324Z","dateUpdated":"2026-03-16T18:17:17.927Z","assignerShortName":"AMZN","assignerOrgId":"ff89ba41-3aa1-4d27-914a-91399e9639e5","dateReserved":"2026-03-16T14:28:58.998Z"},"containers":{"cna":{"title":"AWS API MCP File Access Restriction Bypass","descriptions":[{"lang":"en","value":"Improper Protection of Alternate Path exists in the no-access and workdir feature of the AWS API MCP Server versions >= 0.2.14 and < 1.3.9 on all platforms may allow the bypass of intended file access restriction and expose arbitrary local file contents in the MCP client application context.\n\nTo remediate this issue, users should upgrade to version 1.3.9."}],"affected":[{"vendor":"AWS","product":"AWS API MCP Server","defaultStatus":"unaffected","versions":[{"version":"0.2.14","status":"affected","lessThan":"1.3.9","versionType":"custom"}]}],"references":[{"url":"https://aws.amazon.com/security/security-bulletins/2026-007-AWS/","tags":["vendor-advisory"]},{"url":"https://pypi.org/project/awslabs.aws-api-mcp-server/1.3.9/","tags":["patch"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"version":"3.1","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"NONE","baseSeverity":"MEDIUM","baseScore":5.5,"vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N"}},{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"LOCAL","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"HIGH","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"MEDIUM","baseScore":6.8,"vectorString":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-424","lang":"en","description":"CWE-424: Improper Protection of Alternate Path","type":"CWE"}]}],"providerMetadata":{"shortName":"AMZN","orgId":"ff89ba41-3aa1-4d27-914a-91399e9639e5","dateUpdated":"2026-03-16T16:17:11.659Z"},"impacts":[{"capecId":"CAPEC-6","descriptions":[{"lang":"en","value":"CAPEC-6 Argument Injection"}]}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 1.0.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-03-16T18:17:07.044936Z","id":"CVE-2026-4270","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-03-16T18:17:17.927Z"}}]}}}