Vulnerability in @opennextjs/cloudflare (CVE-2026-100409)
Summary
Vulnerability in @opennextjs/cloudflare (CVE-2026-100409). Confidential information can be exposed externally. Exploitable via enableCacheInterception. Mitigation: upgrade to 1.20.2 or later.
Original description
The description as published by the source.
Summary
When cache interception is enabled, @opennextjs/cloudflare can interpret percent-encoded paths differently during middleware matching and cache lookup.
An encoded request may fail to match authorization middleware, then be decoded into the cache key of a protected route. The cached response may consequently be returned without invoking the middleware.
enableCacheInterception is disabled by default.
Impact
A remote unauthenticated attacker may retrieve cached content from routes intended to be protected by middleware.
An application is affected when it:
- explicitly enables
enableCacheInterception; - relies on middleware for access control; and
- has a matching cached route.
Details
Middleware matching previously used the encoded request pathname, while cache interception decoded the pathname before selecting a cache entry.
For example, consider an application with:
- middleware matcher
/admin/:path*; - middleware returning
401 Authentication requiredfor/admin; - a statically generated, cached
/adminroute; and - cache interception enabled:
export default defineCloudflareConfig({
incrementalCache: staticAssetsIncrementalCache,
enableCacheInterception: true,
});
An attacker can request:
GET /%61dmin
The encoded pathname does not match /admin/:path*, so the authorization middleware is not invoked. Cache interception then decodes %61dmin to admin and may return the cached /admin response:
H…
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-2026-100409 has been found in @opennextjs/cloudflare.
Attackers can target a specific entry point like enableCacheInterception over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.5/10.
What to do: upgrade @opennextjs/cloudflare to 1.20.2 or later.
If unsure, ask your IT team or search "@opennextjs/cloudflare CVE-2026-100409" on the vendor's site.
CVE-2026-100409 (@opennextjs/cloudflare) — CWE-177 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: enableCacheInterception / admin
Patched: 1.20.2 — apply immediately
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.
A vulnerability (CWE-177) exists in @opennextjs/cloudflare. Attackers reach the vulnerable code path via enableCacheInterception without authentication.
Check the vendor advisory for the affected versions of @opennextjs/cloudflare. Attack surface: enableCacheInterception / admin.
Severity: High (CVSS 7.5/10). Confidential information can be exposed externally.
Update to 1.20.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r '@opennextjs/cloudflare' . 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
-
1Identify exposure identify
grep -r '@opennextjs/cloudflare' . | 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
@opennextjs/cloudflareを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade @opennextjs/cloudflare to 1.20.2ステージング環境で 1.20.2 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。
-
3Post-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。