CVE-2026-44573

Summary

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.

Affected Software

VendorProductVersion RangeStatus
vercelnext.js>= 12.2.0, < 15.5.16affected
vercelnext.js>= 16.0.0, < 16.2.5affected

Weaknesses

  • CWE-863: CWE-863: Incorrect Authorization

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

next.js: Next.js: Information disclosure due to middleware bypass in Pages Router with i18n

Additional References

References