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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
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.
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.
Upgrade, and never evaluate templates, expressions or code built from user input. More about Code injection.
Is CVE-2026-103036 being exploited?
There is no known exploitation of CVE-2026-103036 in the wild and no public exploit code.
Sources
Also known as GHSA-4h5r-cv8j-4456.