GHSA-jfgf-83c5-2c4m — i18next-http-middleware
HIGHGHSA-jfgf-83c5-2c4m is a high-severity (CVSS 8.2) Path Traversal vulnerability in i18next-http-middleware. A fix is available for i18next-http-middleware — see the affected versions and patch details below.
i18next-http-middleware has path traversal / SSRF via user-controlled language and namespace parameters
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-jfgf-83c5-2c4m.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-jfgf-83c5-2c4m plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
i18next-http-middlewarenpmDescription
Summary
Versions of i18next-http-middleware prior to 3.9.3 pass the user-controlled lng and ns values from getResourcesHandler directly into i18next.services.backendConnector.load(languages, namespaces, …) without any sanitisation. Depending on which backend is configured, the unvalidated path segments enable one of two attacks:
- Filesystem path traversal when the middleware is paired with
i18next-fs-backend(or any backend that interpolateslng/nsinto a filesystem path). - Server-Side Request Forgery (SSRF) when the middleware is paired with
i18next-http-backend(or any backend that interpolates into an HTTP URL).
Example request:
GET /locales/resources.json?lng=../../etc/passwd&ns=root
with i18next-fs-backend reads the attacker-chosen file from disk; with i18next-http-backend reshapes the outgoing URL to target an internal service.
Impact
- Arbitrary file read via
fs-style backends — any file the Node process can read becomes reachable (source, configuration,.sshkeys,.env, Docker secrets, etc.). - SSRF via
http-style backends — requests to internal IPs / hostnames not normally reachable from the internet; combined with cloud metadata endpoints this can escalate to credential theft. - Unbounded growth of
i18next.options.ns— a now-incidental amplification: the pre-patchgetResourcesHandlerpushed every uniquensvalue into the sharedi18next.options.nssingleton array without validation or bounds, enabling memory exhaustion from repeated unique payloads.
The severity is bounded by the backend in place, but the middleware itself exposed the unsanitised path; this is the "weakest link" layer.
Affected versions
< 3.9.3.
Patch
Fixed in 3.9.3. The patch introduces utils.isSafeIdentifier and applies it in getResourcesHandler before lng and ns reach the backend connector:
languages = languages.filter(utils.isSafeIdentifier)
namespaces = namespaces.filter(utils.isSafeIdentifier)
isSafeIdentifier uses a denylist approach — it still accepts any legitimate i18next language-code shape (i18next FAQ) — rejecting:
..sequences (relative path traversal)- path separators (
/,\) - control characters (C0/C1)
- prototype keys (
__proto__/constructor/prototype) - empty strings and values longer than 128 characters
Unsafe values are dropped; only safe values reach the backend. The fix is a defence-in-depth layer on top of any sanitisation the backend itself may apply.
Workarounds
No workaround short of upgrading. Front-proxying the middleware with a WAF rule that rejects requests containing .., /, \, or URL-structure characters in lng / ns is a partial mitigation. Upgrading the configured backend (i18next-fs-backend ≥ 2.6.4, i18next-http-backend ≥ 3.0.5) also closes the same attack at the next layer.
Related advisories fixed in the same release
- GHSA-5fgg-jcpf-8jjw — prototype pollution via
setPathandmissingKeyHandler. Independently fixable, filed separately per CNA rules. - GHSA-c3h8-g69v-pjrg — HTTP response splitting + XSS-filter bypass (CVE-2026-41683).
Credits
Discovered via an internal security audit of the i18next ecosystem.
Resources
- CWE-22: Path Traversal
- CWE-918: Server-Side Request Forgery (SSRF) (specific sub-case when paired with an HTTP backend)
- i18next FAQ: language code formatting
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | i18next-http-middleware | all versions | 3.9.3npm install i18next-http-middleware@3.9.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for i18next-http-middleware, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update i18next-http-middleware to 3.9.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jfgf-83c5-2c4m is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-jfgf-83c5-2c4m can be triaged on real exposure rather than presence alone.
Tailored to GHSA-jfgf-83c5-2c4m. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-jfgf-83c5-2c4m in your dependencies?
O3 Security finds GHSA-jfgf-83c5-2c4m across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.