@adonisjs/bodyparser has an incomplete fix for CVE-2026-25754

### Summary The fix for [GHSA-f5x2-vj4h-vg4c](https://github.com/adonisjs/core/security/advisories/GHSA-f5x2-vj4h-vg4c) / CVE-2026-25754 introduced in commit [`40e1c71`](https://github.com/adonisjs/bodyparser/commit/40e1c71f958cffb74f6b91bed6630dca979062ed) is incomplete and can be bypassed through nested prototype pollution payloads. The original patch replaced the internal `FormFields` storage object with `Object.create(null)`, preventing direct payloads such as `__proto__.polluted`. However, payloads containing a non-dangerous segment before `__proto__` or `constructor.prototype`, such as `user.__proto__.polluted`, still lead to `Object.prototype` pollution. This issue is exploitable remotely through a single unauthenticated `multipart/form-data` request using the default configuration. ### Affected versions - `>= 10.1.3 < 10.1.5` - `>= 11.0.0-next.9 < 11.0.3` ### Details The regression tests added by the original fix only covered direct payloads such as: - `__proto__.polluted` - `constructor.prototype.polluted` These payloads are blocked because the root object no longer inherits from `Object.prototype`. However, lodash `_.set()` (via `@poppinss/utils`) still creates intermediate objects using plain `{}` values. Once a normal segment is encountered, subsequent `__proto__` or `constructor.prototype` segments regain access to `Object.prototype`. ### Impact An unauthenticated attacker can remotely pollute `Object.prototype` on any route accepting multipart/form-data requests behind `BodyParserMiddleware`. Because the pollution is process-wide, the impact may include authorization bypasses, unexpected behavior in downstream libraries, or prototype pollution gadget chains leading to remote code execution. ### Patches Fixes targeting v6 and v7 have been published below. Users should upgrade to a version that includes the following fix: - https://github.com/adonisjs/bodyparser/releases/tag/v10.1.5 - https://github.com/adonisjs/bodyparser/releases/tag/v11.0.3 ### References - [CWE-1321](https://cwe.mitre.org/data/definitions/1321.html) - Prior advisory this bypasses: [GHSA-f5x2-vj4h-vg4c](https://github.com/adonisjs/core/security/advisories/GHSA-f5x2-vj4h-vg4c) / CVE-2026-25754

Source published

30 Jun 2026 18:34:32 UTC

Source modified

10 Sep 2026 03:50:50 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Publisher rating · HIGH