# CVE-2026-103036: @orpc/json-schema: Prototype injection in smart coercion

> Remote attackers can inject prototype properties in oRPC JSON schema coercion to bypass validation and potentially execute code or alter configuration lookups.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 2 Oct 2026
- **Updated:** 5 Oct 2026
- **Also known as:** GHSA-4h5r-cv8j-4456

## What is CVE-2026-103036?

CVE-2026-103036 is a medium-severity code injection vulnerability in middleapi orpc, published on 2 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

oRPC is a tool that helps build APIs that are end-to-end type-safe and adhere to OpenAPI standards. Prior to 1.14.9, the @orpc/json-schema SmartCoercionPlugin uses JsonSchemaCoercer to collect object properties in a plain object and to resolve schema.properties entries through the prototype chain. A remote client that can reach a procedure with an object input schema can supply __proto__ to replace the prototype of the single coerced request object, or supply Object.prototype member names such as constructor and toString so inherited values are treated as sub-schemas and pass the coercer's satisfaction check. Attacker-controlled inherited properties can consequently affect handler, Object.assign, or configuration lookups, while legitimate __proto__ properties are dropped. The global Object.prototype, unrelated objects, other requests, and other users are not modified, and downstream schema validation still runs. This issue is fixed in version 1.14.9.

Weakness: CWE-915 (Improperly Controlled Modification of Dynamically-Determined Object Attributes), CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-103036?


## How do I fix CVE-2026-103036?

No fix has been published for CVE-2026-103036 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-103036 being exploited?

There is no known exploitation of CVE-2026-103036 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-103036 and fix it if it is affected.

What it is: CVE-2026-103036 is a medium-severity code injection vulnerability in middleapi orpc, published on 2 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-2026-103036 in the wild and no public exploit code.

Affected product: middleapi orpc. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-103036/ (Markdown: https://insights.sbomify.com/CVE-2026-103036/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-103036
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-103036
- OSV: https://osv.dev/vulnerability/CVE-2026-103036

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-103036/
Summaries are generated and may contain mistakes; the official description above is the record.