Prototype pollution in i18next-fs-backend - #VU164413
Published: November 10, 2026
Vulnerability identifier: #VU164413
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-1321
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service lasting for the lifetime of the application process.
The vulnerability exists due to prototype pollution through inherited-property traversal in i18next-fs-backend's getLastOfPath function when processing missing-key writes or queued language/namespace paths. A remote attacker can submit {"hasOwnProperty.call":"PWNED"} to a missing-key write route with saveMissing enabled to overwrite Object.prototype.hasOwnProperty.call and cause subsequent requests to fail.
Affected software
i18next-fs-backend
Remediation
Install security update from vendor's website.
i18next-fs-backend - update to 2.6.8