# CVE-2026-125116: Mongoose discriminator key inheritance bypass

Source: https://junglewise.ai/threats/cve-2026-125116-mongoose-discriminator-key-values-matching-inherited-properties  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-09. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-125116 · Severity: medium · CVSS 4.8 · Published 2026-11-09

Mongoose is a popular object data mapper for MongoDB. An attacker can manipulate discriminator key values (like `__t: 'constructor'`) to bypass schema validation and type casting, potentially poisoning database collections with unvalidated data. This could allow unauthorized fields to persist in documents or cause application crashes when querying affected data.

Technologies: [mongoose (npm)](https://junglewise.ai/threats/technologies/mongoose). Vendors: [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-125116 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-125116 being exploited in the wild.

**How severe is CVE-2026-125116?** Medium severity, with a CVSS score of 4.8, published 9 November 2026.

**Which products and versions are affected?** Mongoose <unknown; mongoose (npm) < 6.13.12, SEMVER:introduced=0,fixed=6.13.12.

**Is there a fix for CVE-2026-125116?** Yes. mongoose (npm): upgrade to 6.13.12 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-125116 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-125116?** Check whether you run Mongoose or mongoose (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- mongoose (npm): upgrade to 6.13.12 or later

  ```sh
  npm install mongoose@6.13.12
  ```


## Technical details

Mongoose's discriminator lookup uses plain object property access on registries without checking for inherited properties, allowing values like 'constructor' or 'toString' to resolve to Object.prototype methods. When combined with `bulkWrite(..., { skipValidation: true })`, raw unvalidated documents can be persisted directly to MongoDB. Query results containing such documents may throw errors during hydration, causing denial of service across all users until the document is manually removed.

## Affected products

- Mongoose Mongoose <unknown

## Identifiers

- CVE-2026-125116
- GHSA-wr5m-5jph-8m96

## Timeline

- 2026-11-10: disclosed

## Related threats

- [Mongoose sanitizeFilter not applied on countDocuments](https://junglewise.ai/threats/cve-2026-125120-mongoose-sanitizefilter-not-applied-on-countdocuments)
- [Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment. From 6.0.0 until 6.13.12, 7.8.13, 8.24.7, and 9.](https://junglewise.ai/threats/cve-2026-125119-mongoose-connection-level-sanitizefilter-not-applied)
- [Mongoose prototype pollution in Schema.prototype.virtual()](https://junglewise.ai/threats/cve-2026-125118-mongoose-prototype-pollution-via-schema-prototype-virtual)
- [Mongoose prototype pollution in object initialization](https://junglewise.ai/threats/cve-2026-125117-mongoose-is-a-mongodb-object-modeling-tool-designed-to-work-in)
- [Mongoose prototype pollution via __proto__ in update casting](https://junglewise.ai/threats/cve-2026-73562-mongoose-prototype-pollution-via-proto-in-update-casting)