What is CVE-2026-45109?

CVE-2026-45109 is a high-severity vulnerability in Vercel Next.js, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 7.5/10. Published 2026-05-13.

How severe is CVE-2026-45109?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Vercel Next.js

CVE-2026-45109

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…

EPSS: 0.000 (2.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

Affected products

Vercel Next.js — versions >= 15.2.0, < 15.5.17, >= 16.0.0, < 16.2.6

Weakness classification (CWE)

CWE-288 — Authentication Bypass Using an Alternate Path or Channel

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)

Frequently asked questions

What is CVE-2026-45109?: CVE-2026-45109 is a high-severity vulnerability in Vercel Next.js, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 7.5/10. Published 2026-05-13.
How severe is CVE-2026-45109?: High severity. CVSS v3 base score is 7.5 out of 10.