Prototype Pollution in Middleapi Orpc
CVE-2026-103918
oRPC is a tool that helps build APIs that are end-to-end type-safe and adhere to OpenAPI standards. Prior to 1.14.10, the @orpc/zod ZodSmartCoercionPlugin and experimental_ZodSmartCoercionPlugin collect object and record properties in plain objects and resolve shape keys through the prototype chain. A remote client that can reach a procedure with an object or record input can supply __proto__ to replace the prototype of the returned request object, allowing attacker-controlled inherited values to reach application lookups. For object schemas, keys such as constructor, toString, and __proto__ can instead resolve inherited members as Zod schemas and cause an unhandled TypeError before validation. The global Object.prototype, unrelated objects, other requests, and other users are not modified, and the availability effect is limited to crafted requests rather than persistent process-wide state. This issue is fixed in version 1.14.10.
Vulnerability class: Mass Assignment
Published .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Middleapi Orpc — versions < 1.14.10
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-103918?
- CVE-2026-103918 is a medium-severity vulnerability in Middleapi Orpc, classified under Improperly Controlled Modification of Dynamically-Determined Object Attributes. CVSS score: 6.5/10. Published 2026-10-02.
- How severe is CVE-2026-103918?
- Medium severity. CVSS v3 base score is 6.5 out of 10.