{"metadata": {"vulnerability": "CVE-2026-110910", "count": 7, "kinds": {"milestone": 3, "sighting": 1, "kev": 0, "other": 3}}, "data": [{"timestamp": "2026-10-15T03:01:58.840Z", "date_only": false, "value": "2026-10-15T03:01:58.840Z", "kind": "milestone", "label": "Reserved", "source": "cvelistv5", "record": "CVE-2026-110910", "field": "cveMetadata.dateReserved"}, {"timestamp": "2026-10-27T06:42:42.365Z", "date_only": false, "value": "2026-10-27T06:42:42.365Z", "kind": "milestone", "label": "Published", "source": "cvelistv5", "record": "CVE-2026-110910", "field": "cveMetadata.datePublished"}, {"timestamp": "2026-10-27T07:07:39.683Z", "date_only": false, "value": "2026-10-27T07:07:39.683634Z", "kind": "sighting", "label": "Seen", "source": "https://infosec.exchange/users/cve/statuses/117511609330259518", "record": "CVE-2026-110910", "field": "creation_timestamp", "uuid": "0b459499-f98e-4fdb-b6b8-b89e8ab593bd", "content": "CVE-2026-110910 qs.stringify with allowEmptyArrays does not encode the keys of empty arrays, allowing query string parameter injection ### Summary\n`qs.stringify` with `allowEmptyArrays: true` writes the key of an empty array without encoding it, even though keys are encoded by default. A key that contains `&` (or the configured `delimiter`), `=`, or `#` \u2234 becomes query string syntax instead of data, so a caller-supplied key name can add parameters to the serialized query string, or cut it short.\n### Details\nIn `lib/stringify.js`, the `allowEmptyArrays` branch returns `adjustedPrefix + '[]'` early, before the code that passes every other key through `encoder` and `formatter`. So `{ \"x&k=v\": [\"1\"] }` serializes as `x%26k%3Dv%5B0%5D=1`, but `{ \"x&k=v\": [] }` serializes as `x&k=v[]`. The early return applies at any depth (`{ \"a\": { \"b&k=v\": [] } }` gives `a[b&k=v][]`), under every `arrayFormat`, with `allowDots`, and with a custom `encoder`, which is never called for that key. With `encode: false` or `encodeValuesOnly: true`, keys are intentionally left unencoded on every path; those configurations are not affected.\n#### PoC\n```js\nvar qs = require(\"qs\");\nvar query = qs.stringify({ q: \"hi\", \"x&apiKey=evil&y\": [] }, { allowEmptyArrays: true });\n// \"q=hi&x&apiKey=evil&y[]\"\nqs.parse(query);\n// { q: \"hi\", x: \"\", apiKey: \"evil\", y: [\"\"] }\nqs.stringify({ \"x#\": [], z: \"1\" }, { allowEmptyArrays: true });\n// \"x#[]&z=1\": in a URL, everything after \"#\" becomes the fragment\n```\n#### Fix\nApplied in 234d505 on `main` and released as v6.17.0: the key of an empty array goes through `encoder` and `formatter` exactly as the key of any other value does, so `{ \"x&apiKey=evil&y\": [] }` now serializes as `x%26apiKey%3Devil%26y[]`. Keys that need no encoding serialize as before, with two exceptions that match every other path: the brackets of a nested key are now encoded (`a[b][]` becomes `a%5Bb%5D[]`, which `qs.parse` reads identically), and with `encodeDotInKeys`, a dot in the key becomes `%252E` instead of `%2E` (which `decodeDotInKeys` previously misread as nesting).\n### Affected versions\n`>=6.12.0 <6.17.0`, fixed in v6.17.0.\n`allowEmptyArrays` was introduced in f22b2bc and first shipped in v6.12.0, with this early return. Every release from v6.12.0 through v6.16.1 is affected. Earlier versions have no `allowEmptyArrays` option and are not affected.\n### Impact\nAn application that passes an object whose key names come from untrusted input to `qs.stringify` with `allowEmptyArrays: true` (for example, to forward a parsed JSON body or user-selected fields to an upstream service) can have parameters injected into the resulting query string. The injected parameters are not keys of the object, so deleting or overwriting a key on the object (such as setting a trusted `apiKey` after copying the user's fields) does not remove them; whether the attacker's value or the application's wins depends on how the receiving side handles a duplicate parameter. A `#` in such a key ends the query string early when the result is placed in a URL. `allowEmptyArrays` is off by default, and only keys whose value (after any `filter`) is an empty array are affected.\nhttps://www.cve.org/CVERecord?id=CVE-2026-110910https://github.com/ljharb/qs/security/advisories/GHSA-w4cr-vjpx-p82qhttps://github.com/ljharb/qs/commit/234d5051f5071efaa025a7ca9e4d34a56a460a1bhttps://github.com/ljharb/qs/pull/561https://github.com/ljharb/qs/issues/626#ljharb #qs#CVE_2026_110910#bot", "url": "https://infosec.exchange/users/cve/statuses/117511609330259518"}, {"timestamp": "2026-10-27T07:16:32.263Z", "date_only": false, "value": "2026-10-27T07:16:32.263", "kind": "milestone", "label": "Published", "source": "fkie_nvd \u00b7 FKIE_CVE-2026-110910", "record": "FKIE_CVE-2026-110910", "field": "published"}, {"timestamp": "2026-10-27T19:32:36.456Z", "date_only": false, "value": "2026-10-27T19:32:36.456Z", "kind": "other", "label": "Updated", "source": "cvelistv5", "record": "CVE-2026-110910", "field": "cveMetadata.dateUpdated"}, {"timestamp": "2026-10-27T19:32:36.456Z", "date_only": false, "value": "2026-10-27T19:32:36.456Z", "kind": "other", "label": "Updated", "source": "cvelistv5 / harborist", "record": "CVE-2026-110910", "field": "containers.cna.providerMetadata.dateUpdated"}, {"timestamp": "2026-10-27T20:17:12.297Z", "date_only": false, "value": "2026-10-27T20:17:12.297", "kind": "other", "label": "Updated", "source": "fkie_nvd \u00b7 FKIE_CVE-2026-110910", "record": "FKIE_CVE-2026-110910", "field": "lastModified"}]}