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

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-06 · updated 2026-06-17
Weakness: CWE-1321

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.

Affected products

middleapi orpc: before 1.13.6 — fixed in 1.13.6

How to fix

Upgrade to a fixed version: middleapi orpc 1.13.6. Check the vendor advisory for mitigations.

References

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