{"id":"GHSA-grp7-v8xh-rj7h","summary":"gRPC Erlang package vulnerable to Remote Code Execution with attacker-controlled gRPC payloads","details":"### 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 -\u003e \u003cmalicious_code\u003e 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","aliases":["CVE-2026-48853","EEF-CVE-2026-48853"],"modified":"2026-08-26T00:38:22.351289558Z","published":"2026-08-25T18:09:53Z","database_specific":{"severity":"CRITICAL","github_reviewed":true,"github_reviewed_at":"2026-08-25T18:09:53Z","nvd_published_at":"2026-06-15T23:16:45Z","cwe_ids":["CWE-502","CWE-770"]},"references":[{"type":"WEB","url":"https://github.com/elixir-grpc/grpc/security/advisories/GHSA-grp7-v8xh-rj7h"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48853"},{"type":"WEB","url":"https://github.com/elixir-grpc/grpc/pull/540"},{"type":"WEB","url":"https://github.com/elixir-grpc/grpc/commit/272a97a5ea1b46af1819f14a831fcf35fc91f992"},{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-48853.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-2026-48853"}],"affected":[{"package":{"name":"grpc","ecosystem":"Hex","purl":"pkg:hex/grpc"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.4.0"},{"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","0.5.0","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-grp7-v8xh-rj7h/GHSA-grp7-v8xh-rj7h.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"}]}