CVSS v3.1
8.2
EPSS
0.29%
Published
May 8, 2026
Modified
May 12, 2026
Public PoC / Exploit
All weaponized →No public PoC or exploit code indexed for this CVE.
Links to public security research (Exploit-DB, Nuclei, Trickest, GitHub) for defensive use only.
Description
i18next-fs-backend is a backend layer for i18next using in Node.js and for Deno to load translations from the filesystem. Prior to version 2.6.4, i18next-fs-backend substitutes the lng and ns options directly into the configured loadPath / addPath templates and then read / write the resulting file from disk. The interpolation is unencoded and unvalidated, so a crafted lng or ns value — containing .., a path separator, a control character, a prototype key, or simply an unexpectedly long string — allows an attacker who can influence either value to read or overwrite files outside the intended locale directory. When lng / ns are derived from untrusted input (request-scoped i18next instances behind an HTTP layer such as i18next-http-middleware, or any framework that lets the end user pick the language via query string, cookie, or header), a single request such as ?lng=../../../../etc/passwd causes the backend to attempt to read that path. This issue has been patched in version 2.6.4.
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:NWeaknesses (CWE)