{"id":"GHSA-q8gf-9rvj-gmgj","summary":"gRPC Erlang package has unbounded request body accumulation in `read_full_body/3`","details":"### Summary\n\n`'Elixir.GRPC.Server.Adapters.Cowboy.Handler':read_full_body/3` accumulates every received chunk into a single growing binary with no size cap. When the client omits the `grpc-timeout` header, the read timeout resolves to `:infinity`, allowing a slow-trickle attacker to hold the connection open indefinitely while memory grows. A single unauthenticated connection is sufficient to exhaust BEAM memory and crash the node.\n\n### Details\n\nThe read loop in `lib/grpc/server/adapters/cowboy/handler.ex` calls `:cowboy_req.read_body/2` in a recursive loop, concatenating each chunk: `body \u003c\u003e data`. There is no running-total check and no configurable maximum body size. As the loop drains the receive buffer, cowboy issues fresh HTTP/2 `WINDOW_UPDATE` frames, so the client can keep pushing data indefinitely.\n\nThe `grpc-timeout` header is attacker-supplied and optional. When absent, `timeout_left_opt(nil)` returns `:infinity`, so the per-chunk read also has no deadline. The two missing controls compound: a fast client can blast multi-gigabyte payloads directly into memory; a slow client can trickle data forever.\n\n### PoC\n\n1. Start any `grpc` server exposing a unary RPC (no special configuration required).\n2. Open an HTTP/2 connection and send a POST to any unary RPC path with `Content-Type: application/grpc+proto` — omit the `grpc-timeout` header.\n3. Stream a large body (e.g. 1 GiB) in chunks without sending the final `END_STREAM` flag immediately.\n4. Observe BEAM memory growing proportionally to uploaded data with no server-side cap.\n\n### Impact\n\nAffects `grpc` ≥ 0.3.1. No authentication, no special configuration, and no specific RPC method required, the unbounded read is on the default unary ingress path.\n\n### References\n\n* Introduction commit: https://github.com/elixir-grpc/grpc/commit/d1abe70a6cad6dac4a3f8235d883d7c896989560\n* Patch commit: https://github.com/elixir-grpc/grpc/commit/49e18c3ec6bb9afe2f712caad3dbab5c56a68a00","aliases":["CVE-2026-48854","EEF-CVE-2026-48854"],"modified":"2026-08-26T00:38:22.365753202Z","published":"2026-08-25T18:12:05Z","database_specific":{"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-08-25T18:12:05Z","nvd_published_at":"2026-06-15T23:16:45Z","cwe_ids":["CWE-770"]},"references":[{"type":"WEB","url":"https://github.com/elixir-grpc/grpc/security/advisories/GHSA-q8gf-9rvj-gmgj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48854"},{"type":"WEB","url":"https://github.com/elixir-grpc/grpc/pull/542"},{"type":"WEB","url":"https://github.com/elixir-grpc/grpc/commit/49e18c3ec6bb9afe2f712caad3dbab5c56a68a00"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-48854.html"},{"type":"PACKAGE","url":"https://github.com/elixir-grpc/grpc"},{"type":"WEB","url":"https://github.com/elixir-grpc/grpc/releases/tag/v1.0.0"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-48854"}],"affected":[{"package":{"name":"grpc","ecosystem":"Hex","purl":"pkg:hex/grpc"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.3.1"},{"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","0.3.1","0.4.0-alpha.1","0.4.0-alpha.2","0.5.0","0.5.0-beta","0.5.0-beta.1","0.6.0","0.7.0","0.8.0","0.8.1","0.9.0","1.0.0-rc.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-q8gf-9rvj-gmgj/GHSA-q8gf-9rvj-gmgj.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}