CVE-2026-48599
Severity CVSS v4.0:
HIGH
Type:
Unavailable / Other
Publication date:
15/06/2026
Last modified:
16/06/2026
Description
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.<br />
<br />
In &#39;Elixir.GRPC.Server.Transcode&#39;: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.<br />
<br />
This issue affects grpc from 0.8.0 before 1.0.0.
Impact
Base Score 4.0
7.60
Severity 4.0
HIGH
References to Advisories, Solutions, and Tools
- https://cna.erlef.org/cves/CVE-2026-48599.html
- https://github.com/elixir-grpc/grpc/commit/33b6a095dbc91c6dee3c7b90893d7d74952e82e4
- https://github.com/elixir-grpc/grpc/security/advisories/GHSA-mwr4-5g34-j5cq
- https://osv.dev/vulnerability/EEF-CVE-2026-48599
- https://github.com/elixir-grpc/grpc/security/advisories/GHSA-mwr4-5g34-j5cq