Vulnerability in i18next-http-middleware (CVE-2026-41683)
Summary
Vulnerability in i18next-http-middleware (CVE-2026-41683). Data can be tampered with by attackers. Exploitable via i18next. Mitigation: upgrade to 3.9.3 or later.
Original description
The description as published by the source.
i18next-http-middleware is a middleware to be used with Node.js web frameworks like express or Fastify and also for Deno. Prior to version 3.9.3, i18next-http-middleware wrote user-controlled language values into the Content-Language response header after passing them through utils.escape(), which is an HTML-entity encoder that does not strip carriage return, line feed, or other control characters. When the application used an older i18next (< 19.5.0) that still exercised the backward-compatibility fallback at LanguageDetector.js:100 or otherwise produced a raw detected value, CRLF sequences in the attacker-controlled lng parameter reached res.setHeader('Content-Language', ...) verbatim. This issue has been patched in version 3.9.3.
Source: NIST National Vulnerability Database 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-2026-41683 has been found in i18next-http-middleware.
Attackers can target a specific entry point like i18next over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 8.6/10.
What to do: upgrade i18next-http-middleware to 3.9.3 or later.
If unsure, ask your IT team or search "i18next-http-middleware CVE-2026-41683" on the vendor's site.
CVE-2026-41683 (i18next-http-middleware) — CWE-113 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: i18next / lng / Location / ERR_INVALID_CHAR
Patched: 3.9.3 — apply immediately
Workaround: No workaround short of upgrading.
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-113) exists in i18next-http-middleware. Attackers reach the vulnerable code path via i18next without authentication.
Check the vendor advisory for the affected versions of i18next-http-middleware. Attack surface: i18next / lng / Location / ERR_INVALID_CHAR.
Severity: High (CVSS 8.6/10). Data can be tampered with by attackers.
Update to 3.9.3.
Workaround: No workaround short of upgrading.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'i18next-http-middleware' . 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 'i18next-http-middleware' . | 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
i18next-http-middleware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
No workaround short of upgrading.パッチが適用されるまでの応急処置として、No workaround short of upgrading. を実施。回避策の副作用 (機能低下) を確認した上で。
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3Apply patch patch
Upgrade i18next-http-middleware to 3.9.3ステージング環境で 3.9.3 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 github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com
- web github.com