Authorization Flaw in next (CVE-2026-44573)
Summary
Vulnerability in next (CVE-2026-44573). Confidential information can be exposed externally. Exploitable via i18n. Mitigation: upgrade to 16.2.5 or later.
Original description
The description as published by the source.
Impact
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//.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.
Fix
The matcher logic was updated to perform the same match as it would on a non-i18n data route.
Workarounds
If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-44573 has been found in next.
Attackers can target a specific entry point like i18n over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.5/10.
What to do: upgrade next to 16.2.5 or later.
If unsure, ask your IT team or search "next CVE-2026-44573" on the vendor's site.
CVE-2026-44573 (next) — CWE-863 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: i18n
Patched: 16.2.5 — apply immediately
Workaround: If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Incorrect authorization (CWE-863) exists in next. Attackers reach the vulnerable code path via i18n without authentication.
Check the vendor advisory for the affected versions of next. Attack surface: i18n.
Severity: High (CVSS 7.5/10). Confidential information can be exposed externally.
Update to 16.2.5.
Workaround: If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'next' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'next' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
nextを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.パッチが適用されるまでの応急処置として、If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware. を実施。回避策の副作用 (機能低下) を確認した上で。
-
3Apply patch patch
Upgrade next to 16.2.5ステージング環境で 16.2.5 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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4Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- patch security-advisories@github.com
- web github.com
- web github.com
- web github.com
- web access.redhat.com
- web bugzilla.redhat.com
- web security.access.redhat.com
- web access.redhat.com
- web access.redhat.com
- web access.redhat.com
- web access.redhat.com