oRPC: Prototype Pollution in `@orpc/client` via `StandardRPCJsonSerializer` Deserialization

published 2026-03-02 8 mo ago modified 2026-06-17 4 mo ago also GHSA-m272-9rp6-32mc , EUVD-2026-9997

cvss: 9.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.1%; EPSS 1.1% chance of exploitation in 30 days, percentile 64%
public exploits: 0; none known

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.

Patch / fix

fixed in 2 links 1

npm @orpc/client 1.13.6
orpc orpc 1.13.6

github.com/middleapi/orpc@1dba06f commit

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: total
Assessed: 8 mo ago (2026-03-09)

Exploit prediction

1.06% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/middleapi/orpc/security/advisories/GHSA-m272-9rp6-32mc referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	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
CNA	4.0	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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
npm	@orpc/client	<1.13.6	1.13.6

Affected products

middleapi orpc

Classification

Weakness

CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

References

github.com /middleapi/orpc/commit/1dba06fc6f938c2486de303c2fa096bc1c8418b5
web, patch
github.com /middleapi/orpc/security/advisories/GHSA-m272-9rp6-32mc
web, exploit, vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2026-28794
advisory
github.com /middleapi/orpc
package

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary