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CVE-2026-48599 elixir-grpc CVE debrief

CVE-2026-48599 is an Authorization Bypass Through User-Controlled Key vulnerability in elixir-grpc grpc. This vulnerability 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. The issue arises from the way 'Elixir.GRPC.Server.Transcode':map_request/5 (lib/grpc/server/transcode.ex) handles path bindings, giving them the lowest merge precedence. This results in a decoded protobuf struct where the path-bound field carries the attacker-supplied value rather than the router-extracted value, silently bypassing any handler that uses the path-bound field for authorization, multi-tenancy scoping, or ownership checks.

Vendor
elixir-grpc
Product
grpc
CVSS
HIGH 7.6
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-15
Original CVE updated
2026-06-16
Advisory published
2026-06-15
Advisory updated
2026-06-16

Who should care

Users of elixir-grpc grpc from version 0.8.0 before 1.0.0 should be aware of this vulnerability and take necessary actions to mitigate it.

Technical summary

The vulnerability is caused by the use of Map.merge/2 with path bindings as the first argument in 'Elixir.GRPC.Server.Transcode':map_request/5 (lib/grpc/server/transcode.ex), giving them the lowest merge precedence. This allows an attacker to smuggle a conflicting value for any path-bound field via the query string or request body.

Defensive priority

HIGH

Recommended defensive actions

  • Update elixir-grpc grpc to version 1.0.0 or later.
  • Review and update handlers that use path-bound fields for authorization, multi-tenancy scoping, or ownership checks.

Evidence notes

The CVE record and details can be found at [cve-org]. More information is available at [nvd]. Additional references include [ref-4], [ref-5], [ref-6], and [ref-7].

Official resources

CVE-2026-48599 was published on 2026-06-15T23:16:45.377Z and has not been modified since then.