{"items":[{"id":"NVI-00017581","kind":"vulnerability","title":"i18next-fs-backend vulnerable to prototype pollution via crafted missing-key string","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-2933-q333-qg83","CVE-2026-48713"],"plain_summary":"GitHub lists this reviewed advisory for i18next-fs-backend. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-26e8ee4fb20625e30042b6b2c3fe0a06"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"CVSS","as_of":"2026-06-25T17:28:47.000Z","value":"9.1 critical","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-26e8ee4fb20625e30042b6b2c3fe0a06"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-26e8ee4fb20625e30042b6b2c3fe0a06","url":"https://github.com/advisories/GHSA-2933-q333-qg83","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-2933-q333-qg83","publisher":"GitHub Advisory Database","observed_at":"2026-11-05T19:05:53.922Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-26e8ee4fb20625e30042b6b2c3fe0a06"],"technology":"i18next-fs-backend","known_exclusions":[],"conditions_summary":"### Impact\n\n`i18next-fs-backend` ≤ 2.6.5, when used to persist missing translation keys (e.g. via `i18next-http-middleware`'s `missingKeyHandler` exposed to untrusted input), is vulnerable to prototype pollution via crafted missing-key strings.\n\n`Backend.writeFile()` splits each queued missing-key string on the configured `keySeparator` (default `.`) before calling the internal `setPath()` walker. The walker (`getLastOfPath` in `lib/utils.js`) did not guard against unsafe segments, so a key like `\"__proto__.polluted\"` was split into `[\"__proto__\", \"polluted\"]` and walked straight into `Object.prototype`, allowing an attacker to write arbitrary properties onto the global object prototype.\n\nDepending on the host application, polluted prototype properties may cause crashes, corrupted translation behaviour, configuration poisoning, or bypasses of property-based security checks.\n\n### Affected configuration\n\nApplications are directly affected only if **all** of the following hold:\n\n- `i18next-fs-backend` ≤ 2.6.5 is configured as the backend.\n- `i18next-http-middleware`'s `missingKeyHandler` (or another route that forwards untrusted request bodies to `i18next.t(..., { ... })` with `saveMi","public_affected_ranges":["< 2.6.6"]}],"null_published_at":"2026-11-05T19:10:21.422Z","source_updated_at":"2026-06-25T17:28:47.000Z","source_disclosed_at":"2026-06-25T17:28:46.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-11-05T19:05:53.922Z"}],"next_cursor":null,"snapshot_revision":"42594"}