Authorization Bypass Through User-Controlled Key vulnerability in elixir-grpc grpc_server and grpc allows an attacker to make a handler act on a resource other than the one named in the URL of an HTTP-transcoded route, via a request with a gRPC Content-Type.

Only the transcoding clause of GRPC.Server.do_handle_request/4 (grpc_server/lib/grpc/server.ex, and lib/grpc/server.ex before the package split) applies the route's path bindings to the request message. The Cowboy handler picks that clause from the request Content-Type, not from the route. A request to a transcoded URL with application/grpc or application/grpc-web is decoded from the body alone, so every path-bound field takes its value from the body. A gateway, proxy rule or WAF that authorizes on the URL path sees one resource while the handler receives another.

This issue affects grpc_server: from 1.0.0 before 1.1.0; grpc: from 0.8.0 before 1.0.0.
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Fixes

Solution

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Workaround

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History

Fri, 13 Nov 2026 16:15:00 +0000

Type Values Removed Values Added
Description Authorization Bypass Through User-Controlled Key vulnerability in elixir-grpc grpc_server and grpc allows an attacker to make a handler act on a resource other than the one named in the URL of an HTTP-transcoded route, via a request with a gRPC Content-Type. Only the transcoding clause of GRPC.Server.do_handle_request/4 (grpc_server/lib/grpc/server.ex, and lib/grpc/server.ex before the package split) applies the route's path bindings to the request message. The Cowboy handler picks that clause from the request Content-Type, not from the route. A request to a transcoded URL with application/grpc or application/grpc-web is decoded from the body alone, so every path-bound field takes its value from the body. A gateway, proxy rule or WAF that authorizes on the URL path sees one resource while the handler receives another. This issue affects grpc_server: from 1.0.0 before 1.1.0; grpc: from 0.8.0 before 1.0.0.
Title Path bindings ignored for gRPC Content-Types on transcoded routes in elixir-grpc grpc_server
First Time appeared Elixir-grpc
Elixir-grpc grpc
Elixir-grpc grpc Server
Weaknesses CWE-436
CWE-639
CPEs cpe:2.3:a:elixir-grpc:grpc:*:*:*:*:*:*:*:*
cpe:2.3:a:elixir-grpc:grpc_server:*:*:*:*:*:*:*:*
Vendors & Products Elixir-grpc
Elixir-grpc grpc
Elixir-grpc grpc Server
References
Metrics cvssV4_0

{'score': 7.6, 'vector': '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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: EEF

Published:

Updated: 2026-11-13T15:58:08.134Z

Reserved: 2026-11-09T23:03:52.038Z

Link: CVE-2026-124278

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-13T16:17:39.297

Modified: 2026-11-13T16:17:39.297

Link: CVE-2026-124278

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses