{"id":"EEF-CVE-2026-48599","summary":"Authorization bypass via path binding override in elixir-grpc/grpc HTTP transcoding","details":"## Summary\n\nAuthorization 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.\n\nIn '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.\n\nThis issue affects grpc from 0.8.0 before 1.0.0.\n\n## Configurations\n\nHTTP-to-gRPC transcoding must be enabled.","aliases":["CVE-2026-48599","GHSA-mwr4-5g34-j5cq"],"modified":"2026-09-08T03:45:04.804546856Z","published":"2026-06-15T21:55:28.702Z","database_specific":{"cwe_ids":["CWE-639"],"capec_ids":["CAPEC-460"],"cpe_ids":["cpe:2.3:a:elixir-grpc:grpc:*:*:*:*:*:*:*:*"]},"references":[{"type":"ADVISORY","url":"https://github.com/elixir-grpc/grpc/security/advisories/GHSA-mwr4-5g34-j5cq"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-48599.html"},{"type":"FIX","url":"https://github.com/elixir-grpc/grpc/commit/33b6a095dbc91c6dee3c7b90893d7d74952e82e4"},{"type":"PACKAGE","url":"https://hex.pm/packages/grpc"}],"affected":[{"package":{"name":"grpc","ecosystem":"Hex","purl":"pkg:hex/grpc"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.8.0"},{"fixed":"1.0.0"}]}],"versions":["0.10.0","0.10.1","0.10.2","0.11.0","0.11.1","0.11.2","0.11.3","0.11.4","0.11.5","0.8.0","0.8.1","0.9.0","1.0.0-rc.1"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-48599.json"}},{"ranges":[{"type":"GIT","repo":"https://github.com/elixir-grpc/grpc","events":[{"introduced":"8aaf3d3a8c4c7b08ac65e9c6f254e0d24da1d048"},{"fixed":"33b6a095dbc91c6dee3c7b90893d7d74952e82e4"}]}],"versions":["v0.11.2","v0.8.1","v0.8.0"],"database_specific":{"source":"https://cna.erlef.org/osv/EEF-CVE-2026-48599.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}],"credits":[{"name":"Peter Ullrich","type":"FINDER"},{"name":"Paulo Valente","type":"REMEDIATION_DEVELOPER"},{"name":"Jonatan Männchen","type":"ANALYST"}]}