# CVE-2026-104852: GraphQL Tools has prototype pollution in well-established utility function `mergeDeep`

> An attacker can exploit prototype pollution in GraphQL Tools to overwrite Function.prototype.call, leading to code execution or denial of service.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 5 Oct 2026
- **Updated:** 6 Oct 2026
- **Also known as:** CLSA-2026-1791291395, CLSA-2026-1792937883, CLSA-2026-1793018204, CLSA-2026-1793019970, CLSA-2026-1793020728, CLSA-2026-1793021479, CLSA-2026-1793022219, CLSA-2026-1793023448, CLSA-2026-1793047049, CLSA-2026-1793047143, CLSA-2026-1793047238, CLSA-2026-1793113090, CLSA-2026-1793113298, GHSA-7mx3-vvmw-hjmv, MINI-vwq5-23j3-wg35, ROOT-APP-NPM-CVE-2026-104852

## What is CVE-2026-104852?

CVE-2026-104852 is a high-severity code injection vulnerability in ardatan graphql-tools, published on 5 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

GraphQL Tools provides utilities for building, stitching, and mocking GraphQL schemas. Prior to 12.0.1, the GraphQL Tools utils package's mergeDeep function follows inherited properties while recursively merging source objects and does not exclude __proto__, constructor, or prototype keys. An unauthenticated GraphQL client can alias fields to those names so responses from two subgraphs collide during ordinary supergraph result merging, causing mergeDeep to traverse Object and Function prototypes and overwrite Function.prototype.call with a subgraph-supplied value. This breaks subsequent requests in the process until restart. This issue is fixed in version 12.0.1.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-104852?

2 open source packages ship an affected version, including @graphql-tools/utils.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@graphql-tools/utils` | npm | All versions | 12.0.1 |
| `@graphql-tools/utils` | npm | All versions | 12.0.1 |

## How do I fix CVE-2026-104852?

Upgrade @graphql-tools/utils to 12.0.1 or later.

## Is CVE-2026-104852 being exploited?

There is no known exploitation of CVE-2026-104852 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104852 and fix it if it is affected.

What it is: CVE-2026-104852 is a high-severity code injection vulnerability in ardatan graphql-tools, published on 5 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-104852 in the wild and no public exploit code.

Affected packages and fixed versions:
- @graphql-tools/utils (npm): affected all versions; fixed in 12.0.1
- @graphql-tools/utils (npm): affected all versions; fixed in 12.0.1

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-2026-104852/ (Markdown: https://insights.sbomify.com/CVE-2026-104852/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104852
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104852
- OSV: https://osv.dev/vulnerability/CVE-2026-104852

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104852/
Summaries are generated and may contain mistakes; the official description above is the record.