CVE-2026-124278

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.

Is your site exposed to CVE-2026-124278?

Run a free security scan — no signup, results in seconds.

Weakness Type (CWE)

CWE-436 CWE-436

CWE-639 CWE-639

References

Other References

https://cna.erlef.org/cves/CVE-2026-124278.html https://github.com/elixir-grpc/grpc/commit/0332faae5f5e132314794dbfdae5edecbccea292 https://github.com/elixir-grpc/grpc/commit/8aaf3d3a8c4c7b08ac65e9c6f254e0d24da1d048 https://github.com/elixir-grpc/grpc/commit/953ab980d8a127e895d3ab9505fc4b9337bb32f7 https://github.com/elixir-grpc/grpc/security/advisories/GHSA-xc5v-89vq-hv5m https://osv.dev/vulnerability/EEF-CVE-2026-124278

Frequently Asked Questions

What is CVE-2026-124278? +

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.

How do I check if I'm vulnerable to CVE-2026-124278? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-42272

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall handles URL-encoded …

CVE-2025-54368

uv is a Python package and project manager written in Rust. In versions 0.8.5 and earlier, remote ZIP archives were …

CVE-2026-42274

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall performs rule …

CVE-2026-42273

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall performs host …

CVE-2026-47344

When ALLOW_INSECURE_RAW_TEXT is enabled, whitespace-variant closing tags (e.g., </style\t>) are not recognized by the sanitizer but accepted by browsers as …

CVE-2026-44974

@hapi/content provided HTTP Content-* headers parsing. Prior to 6.0.2, Content.disposition() retained the last occurrence of each duplicate parameter while Content.type() …