High

Authorization Bypass in Next.js Dynamic Routes via Middleware Mismatch

IdentifiersCVE-2026-44574CWE-288· Authentication Bypass Using an…

CVE-2026-44574 is a high-severity authorization bypass vulnerability in Next.js affecting applications that rely on middleware to protect dynamic routes. In affected versions, specially crafted query parameters can cause a mismatch between the dynamic route value evaluated by the page and the visible request path evaluated by middleware. As a result, the page can render content for a protected dynamic route even though the expected middleware authorization check was not applied to that effective route value. The issue affects Next.js from 15.4.0 to before 15.5.16 and 16.x before 16.2.5. The flaw is tracked as GHSA-492v-c6pp-mqqv.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can allow an attacker to bypass intended authorization controls on protected dynamic routes and access content that should have been gated by middleware. Based on the provided CVSS vector, the primary impacts are high confidentiality and high integrity, with no direct availability impact stated. In practice, this can expose protected pages or route-specific content and may permit unauthorized interaction with application functionality tied to those routes, depending on how the application uses middleware for access control.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, do not rely solely on middleware path matching to enforce authorization for dynamic routes. Enforce authorization checks within the route handler, page logic, or backend data-access layer using the resolved route parameters and authenticated user context. Review dynamic-route protections for cases where query parameters may influence route resolution, and add server-side validation to ensure the effective route value matches the expected protected resource.

Remediation

Patch, then assume compromise.

Upgrade Next.js to a fixed version. For affected 15.x deployments, update to 15.5.16 or later. For affected 16.x deployments, update to 16.2.5 or later. Validate that middleware-protected dynamic routes behave consistently after upgrade and regression-test authorization logic for route parameter handling.

PUBLIC EXPLOITS

Exploits

No valid public exploits. Mallory filtered out 1 candidate as fakes, detection scripts, or README-only repos.

VALID 0 / 1 TOTALView more in app

All candidate exploits were filtered out by Mallory's validation.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

VercelNextapplication

VercelNext.Jsapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

14 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

14 SOURCESView more in app

cvefeed high severityNews

May 13, 2026

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

An authorization bypass vulnerability in Next.js affecting applications that use middleware to protect dynamic routes. Specially crafted query parameters can manipulate the dynamic route value seen by the page while bypassing the expected middleware authorization check.

What this page doesn’t show

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity13

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-44574

NVD

nvd.nist.gov/vuln/detail/CVE-2026-44574

MITRE CWE · CWE-288

Authentication Bypass Using an Alternate Path…

Vendor Advisory

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