# CVE-2026-28794: oRPC: Prototype Pollution in `@orpc/client` via `StandardRPCJsonSerializer` Deserialization

> Remote attackers can exploit prototype pollution in the oRPC client deserializer to achieve code execution, bypass authentication, or cause denial of service.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/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:** 6 Mar 2026
- **Updated:** 9 Mar 2026
- **Also known as:** GHSA-m272-9rp6-32mc

## What is CVE-2026-28794?

CVE-2026-28794 is a critical unsafe deserialization vulnerability in middleapi orpc, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

oRPC is an tool that helps build APIs that are end-to-end type-safe and adhere to OpenAPI standards. Prior to version 1.13.6, a prototype pollution vulnerability exists in the RPC JSON deserializer of the @orpc/client package. The vulnerability allows unauthenticated, remote attackers to inject arbitrary properties into the global Object.prototype. Because this pollution persists for the lifetime of the Node.js process and affects all objects, it can lead to severe security breaches, including authentication bypass, denial of service, and potentially Remote Code Execution. This issue has been patched in version 1.13.6.

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

## Which versions are affected by CVE-2026-28794?

2 open source packages ship an affected version, including @orpc/client. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `@orpc/client` | npm | All versions | 1.13.6 |
| `@orpc/client` | npm | All versions | 1.13.6 |

Products: Orpc Orpc.

## How do I fix CVE-2026-28794?

Upgrade @orpc/client to 1.13.6 or later.

## Is CVE-2026-28794 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-28794 exists.

## Other vulnerabilities in middleapi orpc

- [CVE-2026-33331](https://insights.sbomify.com/CVE-2026-33331/): oRPC: Stored XSS in OpenAPI Reference Plugin via unescaped JSON.stringify (high 8.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28794 and fix it if it is affected.

What it is: CVE-2026-28794 is a critical unsafe deserialization vulnerability in middleapi orpc, published on 6 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-28794 exists.

Affected packages and fixed versions:
- @orpc/client (npm): affected all versions; fixed in 1.13.6
- @orpc/client (npm): affected all versions; fixed in 1.13.6

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-2026-28794/ (Markdown: https://insights.sbomify.com/CVE-2026-28794/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28794
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28794
- OSV: https://osv.dev/vulnerability/CVE-2026-28794

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28794/
Summaries are generated and may contain mistakes; the official description above is the record.