SB2026090933 - Prototype pollution in i18next-fs-backend

Description

This security bulletin contains information about 1 vulnerability.

1) Prototype pollution (CVE-ID: CVE-2026-48713)

CWE-ID: CWE-1321 - Improperly Controlled Modification of Object Prototype Attributes (\'Prototype Pollution\')

CVSSv4: 8.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to execute arbitrary JavaScript code.

The vulnerability exists due to prototype pollution via crafted missing-key strings when used to persist missing translation keys (e.g. via i18next-http-middleware's missingKeyHandler exposed to untrusted input). A remote attacker can pass specially crafted input to the application and perform prototype pollution, which can result in information disclosure or data manipulation.

Remediation

Install update from vendor's website.

References

• https://github.com/i18next/i18next-fs-backend/commit/3ab0448087da6935a40117f904b7457281f963f4
• https://github.com/i18next/i18next-fs-backend/security/advisories/GHSA-2933-q333-qg83