# CVE-2026-125116: Mongoose: Discriminator key values matching inherited properties (e.g. __t: 'constructor') bypass schema casting and can poison collections


- **Severity:** Medium 4.8 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 9 Nov 2026
- **Updated:** 9 Nov 2026
- **Also known as:** GHSA-wr5m-5jph-8m96

## What is CVE-2026-125116?

CVE-2026-125116 is a medium-severity vulnerability in Automattic mongoose, published on 9 Nov 2026. 

### Official description

Mongoose is a MongoDB object modeling tool designed to work in an asynchronous environment. Prior to 6.13.12, 7.8.13, 8.24.7, and 9.11.4, Mongoose uses attacker-controlled discriminator key values, including the default __t field, to index plain-object registries such as Model.discriminators and schema.discriminators without requiring an own property. Values such as constructor, toString, or hasOwnProperty can therefore resolve to inherited built-in functions instead of a registered discriminator, causing type confusion in model construction, document creation, hydration, query and update casting, embedded discriminators, and populate operations. In the bulkWrite() insertOne path with skipValidation enabled, a constructor value can cause a raw input object to be stored without schema casting or strict filtering, and a stored poisoned document can make every query that hydrates it fail until the document is removed. The weakness reads inherited properties but does not modify Object.prototype and is not prototype pollution. This issue is fixed in versions 6.13.12, 7.8.13, 8.24.7, and 9.11.4.

Weakness: CWE-843 (Access of Resource Using Incompatible Type)

## Which versions are affected by CVE-2026-125116?

4 open source packages ship an affected version, including mongoose.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mongoose` | npm | All versions | 6.13.12 |
| `mongoose` | npm | From 7.0.0 | 7.8.13 |
| `mongoose` | npm | From 8.0.0 | 8.24.7 |
| `mongoose` | npm | From 9.0.0 | 9.11.4 |

## How do I fix CVE-2026-125116?

Upgrade mongoose to a fixed version for your release line: 6.13.12, 7.8.13, 8.24.7 or 9.11.4.

## Is CVE-2026-125116 being exploited?

There is no known exploitation of CVE-2026-125116 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-125116 and fix it if it is affected.

What it is: CVE-2026-125116 is a medium-severity vulnerability in Automattic mongoose, published on 9 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-125116 in the wild and no public exploit code.

Affected packages and fixed versions:
- mongoose (npm): affected all versions; fixed in 6.13.12
- mongoose (npm): affected from 7.0.0; fixed in 7.8.13
- mongoose (npm): affected from 8.0.0; fixed in 8.24.7
- mongoose (npm): affected from 9.0.0; fixed in 9.11.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-125116/ (Markdown: https://insights.sbomify.com/CVE-2026-125116/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-125116
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-125116
- OSV: https://osv.dev/vulnerability/CVE-2026-125116

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-125116/
Summaries are generated and may contain mistakes; the official description above is the record.