Vercel Next.js <15.5.18 & <16.2.6 Middleware.ts Turbopack Vulnerability
CVE-2026-45109 Published on May 13, 2026
Next.js: Middleware / Proxy bypass in App Router applications via segment-prefetch routes
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.
Vulnerability Analysis
CVE-2026-45109 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.
Weakness Types
Authentication Bypass Using an Alternate Path or Channel
A product requires authentication, but the product has an alternate path or channel that does not require authentication.
Improperly Implemented Security Check for Standard
The software does not implement or incorrectly implements one or more security-relevant checks as specified by the design of a standardized algorithm, protocol, or technique.
Products Associated with CVE-2026-45109
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Affected Versions
vercel next.js:- Version >= 15.2.0, < 15.5.17 is affected.
- Version >= 16.0.0, < 16.2.6 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.