Vulnerability in @fastify/static (CVE-2026-6414)
Summary
Vulnerability in @fastify/static (CVE-2026-6414). Confidential information can be exposed externally. Mitigation: upgrade to 9.1.1 or later.
Original description
The description as published by the source.
Impact
@fastify/static v9.1.0 and earlier decodes percent-encoded path separators (%2F) before filesystem resolution, but Fastify's router treats them as literal characters. This creates a routing mismatch: route guards on /admin/* do not match /admin%2Fsecret.html, but @fastify/static decodes it to /admin/secret.html and serves the file.
Applications that rely on route-based middleware or guards to protect files served by @fastify/static can be bypassed with encoded path separators.
Patches
Upgrade to @fastify/static >= 9.1.1.
Workarounds
None. Upgrade to the patched version.
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
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-2026-6414 has been found in @fastify/static.
Confidential information can be exposed externally.
What to do: upgrade @fastify/static to 9.1.1 or later.
If unsure, ask your IT team or search "@fastify/static CVE-2026-6414" on the vendor's site.
CVE-2026-6414 (@fastify/static) — CWE-177
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 9.1.1 — apply immediately
Workaround: None.
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 @fastify/static.
Check the vendor advisory for the affected versions of @fastify/static.
Severity: ?. Confidential information can be exposed externally.
Update to 9.1.1.
Workaround: None.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r '@fastify/static' . 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 '@fastify/static' . | 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
@fastify/static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
None.パッチが適用されるまでの応急処置として、None. 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 @fastify/static to 9.1.1ステージング環境で 9.1.1 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。
-
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
- web github.com
- web github.com
- web github.com
- web cna.openjsf.org