{"id":"CVE-2026-48854","aliases":["GHSA-q8gf-9rvj-gmgj"],"title":"gRPC Erlang package has unbounded request body accumulation in `read_full_body/3`","summary":"gRPC Erlang package has unbounded request body accumulation in `read_full_body/3`","severity":"high","cwe":["CWE-770"],"vendor":"grpc","product":"grpc","ecosystem":"erlang","affected":["grpc >= 0.3.1, < 1.0.0"],"patched":["grpc 1.0.0"],"published":"2026-08-25","updated":"2026-08-25","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-q8gf-9rvj-gmgj","references":[{"url":"https://github.com/elixir-grpc/grpc/security/advisories/GHSA-q8gf-9rvj-gmgj"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48854"},{"url":"https://github.com/elixir-grpc/grpc/pull/542"},{"url":"https://github.com/elixir-grpc/grpc/commit/49e18c3ec6bb9afe2f712caad3dbab5c56a68a00"},{"url":"https://cna.erlef.org/cves/CVE-2026-48854.html"},{"url":"https://github.com/elixir-grpc/grpc/releases/tag/v1.0.0"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-48854"},{"url":"https://github.com/advisories/GHSA-q8gf-9rvj-gmgj"}],"tags":["ghsa","erlang"],"epss":0.00344,"epssPercentile":0.27902,"ingestedAt":"2026-08-25T18:30:21.233Z","slug":"CVE-2026-48854","body":"## Overview\n\n### 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 <> 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\n\n## Affected packages\n\n- `grpc >= 0.3.1, < 1.0.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `grpc 1.0.0`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}