CVE-2026-48854: Grpc GRPC Erlang Package Has Unbounded Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-q8gf-9rvj-gmgj",
  "modified" : "2026-08-25T18:12:05Z",
  "published" : "2026-08-25T18:12:05Z",
  "aliases" : [ "CVE-2026-48854" ],
  "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 <> 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",
  "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Hex",
      "name" : "grpc"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.3.1"
      }, {
        "fixed" : "1.0.0"
      } ]
    } ]
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-25T18:12:05Z",
    "nvd_published_at" : "2026-06-15T23:16:45Z"
  }
}