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CVE-2026-44573— Next.js: Middleware / Proxy bypass in Pages Router applications using i18n

Quick assessment

Affected
vercel next.js
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Next.js是Vercel开源的一个 React 框架。 Next.js 12.2.0至15.5.16之前版本和16.2.5之前版本存在安全漏洞，该漏洞源于使用Pages Router且配置i18n和中间件或代理授权时，未对无语言前缀的/_next/data/<buildId>/<page>.json请求执行中间件，可能导致未经授权的访问受保护页面数据。

CVSS 7.5 · High EPSS 0.76% · P54

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
vercel next.js >= 12.2.0, < 15.5.16 affected
>= 16.0.0, < 16.2.5 affected
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I. Basic Information for CVE-2026-44573

Vulnerability Information
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Vulnerability Title
Next.js: Middleware / Proxy bypass in Pages Router applications using i18n
Source: CVE Program / CVE List V5
Vulnerability Description
Next.js is a React framework for building full-stack web applications. From 12.2.0 to before 15.5.16 and 16.2.5, Applications using the Pages Router with i18n configured and middleware/proxy-based authorization can allow unauthorized access to protected page data through locale-less /_next/data/<buildId>/<page>.json requests. In affected configurations, middleware does not run for the unprefixed data route, allowing an attacker to retrieve SSR JSON for protected pages without passing the intended authorization checks. This vulnerability is fixed in 15.5.16 and 16.2.5.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制不正确
Source: CVE Program / CVE List V5
Vulnerability Title
Next.js 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Next.js是Vercel开源的一个 React 框架。 Next.js 12.2.0至15.5.16之前版本和16.2.5之前版本存在安全漏洞，该漏洞源于使用Pages Router且配置i18n和中间件或代理授权时，未对无语言前缀的/_next/data/<buildId>/<page>.json请求执行中间件，可能导致未经授权的访问受保护页面数据。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
vercel next.js >= 12.2.0, < 15.5.16 -

II. Public POCs for CVE-2026-44573

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III. Intelligence Information for CVE-2026-44573

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Vendor Advisories for CVE-2026-44573 (1)

Same Patch Batch · vercel · 2026-05-13 · 13 CVEs total

CVE-2026-44578 8.6 HIGH Next.js: Server-side request forgery in applications using WebSocket upgrades
CVE-2026-44574 8.1 HIGH Next.js: Middleware / Proxy bypass through dynamic route parameter injection
CVE-2026-45109 7.5 HIGH Next.js: Middleware / Proxy bypass in App Router applications via segment-prefetch routes
CVE-2026-44579 7.5 HIGH Next.js: Denial of Service via connection exhaustion in applications using Cache Component
CVE-2026-44575 7.5 HIGH Next.js: Middleware / Proxy bypass in App Router applications via segment-prefetch routes
CVE-2026-44580 6.1 MEDIUM Next.js: Cross-site scripting in beforeInteractive scripts with untrusted input
CVE-2026-44577 5.9 MEDIUM Next.js: Denial of Service in the Image Optimization API
CVE-2026-44479 5.5 MEDIUM Vercel: Non-interactive mode includes CLI arguments in suggested command output
CVE-2026-44576 5.4 MEDIUM Next.js: Cache poisoning in React Server Component responses
CVE-2026-44581 4.7 MEDIUM Next.js: Cross-site scripting in App Router applications using CSP nonces
CVE-2026-44572 3.7 LOW Next.js: Middleware / Proxy redirects can be cache-poisoned
CVE-2026-44582 3.7 LOW Next.js: Cache poisoning via collisions in React Server Component cache-busting

IV. Related Vulnerabilities

Same product: next.js
Same vendor: vercel
Same weakness: CWE-863

V. Comments for CVE-2026-44573

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