---
id: CVE-2026-48599
title: >-
  Authorization Bypass Through User-Controlled Key vulnerability in elixir-grpc
  grpc allows authenticated attackers to access or modify resources belonging to
  other users by smuggling a conflicting value for any path-bound field via the
  qu…
summary: >-
  Authorization Bypass Through User-Controlled Key vulnerability in elixir-grpc
  grpc allows authenticated attackers to access or modify resources belonging to
  other users by smuggling a conflicting value for any path-bound field via the
  qu…
severity: high
cvss: 7.6
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'
cwe:
  - CWE-639
vendor: elixir-grpc
product: grpc
affected:
  - grpc >= 0.8.0 < 1.0.0
  - >-
    elixir-grpc/grpc >= 8aaf3d3a8c4c7b08ac65e9c6f254e0d24da1d048 <
    33b6a095dbc91c6dee3c7b90893d7d74952e82e4
patched:
  - grpc 1.0.0
published: '2026-06-15'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T21:17:13.967'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48599'
references:
  - url: 'https://cna.erlef.org/cves/CVE-2026-48599.html'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-grpc/grpc/commit/33b6a095dbc91c6dee3c7b90893d7d74952e82e4
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-grpc/grpc/commit/8aaf3d3a8c4c7b08ac65e9c6f254e0d24da1d048
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-grpc/grpc/security/advisories/GHSA-mwr4-5g34-j5cq
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: 'https://osv.dev/vulnerability/EEF-CVE-2026-48599'
    label: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
  - url: >-
      https://github.com/elixir-grpc/grpc/security/advisories/GHSA-mwr4-5g34-j5cq
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-48599'
  - url: 'https://github.com/elixir-grpc/grpc/pull/541'
  - url: 'https://github.com/elixir-grpc/grpc/releases/tag/v1.0.0'
  - url: 'https://github.com/advisories/GHSA-mwr4-5g34-j5cq'
tags:
  - nvd
  - cve.org
  - exploit-available
  - ghsa
  - erlang
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-06-16T14:45:46.288762Z'
cvssSource: cna
epss: 0.00449
epssPercentile: 0.36298
aliases:
  - GHSA-mwr4-5g34-j5cq
ecosystem: erlang
ingestedAt: '2026-08-25T18:30:21.273Z'
---

## Overview

Authorization Bypass Through User-Controlled Key vulnerability in elixir-grpc grpc allows authenticated attackers to access or modify resources belonging to other users by smuggling a conflicting value for any path-bound field via the query string or request body.

In 'Elixir.GRPC.Server.Transcode':map_request/5 (lib/grpc/server/transcode.ex), all three clauses use Map.merge/2 with path bindings as the first argument, giving them the lowest merge precedence. A request such as GET /users/me/profile?user_id=victim (or a POST with {"user_id": "victim"} when body: "*") yields a decoded protobuf struct where the path-bound field carries the attacker-supplied value rather than the router-extracted value. Any handler that uses the path-bound field for authorization, multi-tenancy scoping, or ownership checks is silently bypassed.

This issue affects grpc: from 0.8.0 before 1.0.0.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-48599)

Affected packages:

- `grpc >= 0.8.0, < 1.0.0`

Patched in:

- `grpc 1.0.0`

Source: https://github.com/advisories/GHSA-mwr4-5g34-j5cq