{"id":"CVE-2026-48853","aliases":["GHSA-grp7-v8xh-rj7h"],"title":"gRPC Erlang package vulnerable to Remote Code Execution with attacker-controlled gRPC payloads","summary":"gRPC Erlang package vulnerable to Remote Code Execution with attacker-controlled gRPC payloads","severity":"critical","cwe":["CWE-502","CWE-770"],"vendor":"grpc","product":"grpc","ecosystem":"erlang","affected":["grpc >= 0.4.0, < 1.0.0"],"patched":["grpc 1.0.0"],"published":"2026-08-25","updated":"2026-08-25","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-grp7-v8xh-rj7h","references":[{"url":"https://github.com/elixir-grpc/grpc/security/advisories/GHSA-grp7-v8xh-rj7h"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48853"},{"url":"https://github.com/elixir-grpc/grpc/pull/540"},{"url":"https://github.com/elixir-grpc/grpc/commit/272a97a5ea1b46af1819f14a831fcf35fc91f992"},{"url":"https://cna.erlef.org/cves/CVE-2026-48853.html"},{"url":"https://github.com/elixir-grpc/grpc/releases/tag/v1.0.0"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-48853"},{"url":"https://github.com/advisories/GHSA-grp7-v8xh-rj7h"}],"tags":["ghsa","erlang"],"epss":0.00573,"epssPercentile":0.45846,"ingestedAt":"2026-08-25T18:30:21.311Z","slug":"CVE-2026-48853","body":"## Overview\n\n### Summary\n\n`GRPC.Codec.Erlpack.decode/2` calls `:erlang.binary_to_term/1` directly on the raw gRPC message body without the `:safe` option. Any unauthenticated peer that can reach a gRPC endpoint with `Content-Type: application/grpc+erlpack` can crash the entire BEAM node via atom table exhaustion or, if a decoded fun term flows into a call site that invokes it, achieve remote code execution inside the server process.\n\n### Details\n\n**Root cause** — `lib/grpc/codec/erlpack.ex` implements `decode/2` as a bare `:erlang.binary_to_term(binary)` call with no `:safe` flag, no size limit, and no type validation. This has two independent exploitation paths:\n\n**1. DoS via atom exhaustion** — BEAM atoms are never garbage-collected and the global atom table is bounded (~1,048,576 entries). A crafted payload encoding large numbers of fresh atoms saturates the table and crashes the entire VM, taking down all applications on the node.\n\n**2. RCE via fun materialization** — Without `:safe`, `binary_to_term/1` reconstructs fun and external-fun terms from wire data. If the decoded value reaches any call site that applies it (e.g. `Enum.map`, `Task.async`, direct invocation), attacker-controlled code executes inside the server process.\n\n**Configuration requirement:** `GRPC.Codec.Erlpack` is not registered by default and must be explicitly added to the server's `codecs` option.\n\n### PoC\n\n1. Start a gRPC server with `codecs: [GRPC.Codec.Erlpack]`.\n2. Open an HTTP/2 connection to the server.\n3. Send a gRPC-framed POST to any RPC path with `Content-Type: application/grpc+erlpack` and a body of `:erlang.term_to_binary(fn -> <malicious_code> end)`.\n4. The server's `decode/2` materializes the fun; any downstream call site that invokes the decoded value executes the attacker's code.\n5. For DoS only: send payloads encoding fresh atoms in a loop until the atom table is exhausted and the VM crashes.\n\n### Impact\n\nAffects `grpc` ≥ 0.4.0. Any server that explicitly registers `GRPC.Codec.Erlpack` is vulnerable to unauthenticated node-level DoS and potentially RCE.\n\n### References\n\n* Introduction commit: https://github.com/elixir-grpc/grpc/commit/25bcc569fe2cc4478531a6c546c923205fc751c9\n* Patch commit: https://github.com/elixir-grpc/grpc/commit/272a97a5ea1b46af1819f14a831fcf35fc91f992\n\n## Affected packages\n\n- `grpc >= 0.4.0, < 1.0.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `grpc 1.0.0`","depth":"midnight","depthScore":52,"depthScoreParts":{"impact":52.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}