{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-71397", "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "state": "PUBLISHED", "assignerShortName": "EEF", "dateReserved": "2026-08-19T10:30:01.929Z", "datePublished": "2026-11-06T21:02:03.676Z", "dateUpdated": "2026-11-06T21:02:03.676Z"}, "containers": {"cna": {"affected": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:elixir-grpc:grpc_server:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.GRPC.Server.Adapters.Cowboy.Handler'", "'Elixir.GRPC.Server.Adapters.Cowboy'"], "packageName": "grpc_server", "packageURL": "pkg:hex/grpc_server", "product": "grpc_server", "programFiles": ["lib/grpc/server/adapters/cowboy/handler.ex", "lib/grpc/server/adapters/cowboy.ex"], "programRoutines": [{"name": "'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3"}, {"name": "'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1"}], "repo": "https://github.com/elixir-grpc/grpc", "vendor": "elixir-grpc", "versions": [{"lessThan": "1.0.6", "status": "affected", "version": "1.0.0", "versionType": "semver"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:elixir-grpc:grpc_server:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.GRPC.Server.Adapters.Cowboy.Handler'", "'Elixir.GRPC.Server.Adapters.Cowboy'"], "packageName": "elixir-grpc/grpc", "packageURL": "pkg:github/elixir-grpc/grpc", "product": "grpc_server", "programFiles": ["grpc_server/lib/grpc/server/adapters/cowboy/handler.ex", "grpc_server/lib/grpc/server/adapters/cowboy.ex"], "programRoutines": [{"name": "'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3"}, {"name": "'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1"}], "repo": "https://github.com/elixir-grpc/grpc", "vendor": "elixir-grpc", "versions": [{"lessThan": "0b663ca53dbf0f36f7f67ff1d0026f4482a18915", "status": "affected", "version": "49e18c3ec6bb9afe2f712caad3dbab5c56a68a00", "versionType": "git"}]}], "configurations": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>The server must expose at least one client-streaming or bidirectional-streaming RPC method.</p>"}, {"base64": false, "type": "text/markdown", "value": "The server must expose at least one client-streaming or bidirectional-streaming RPC method."}], "value": "The server must expose at least one client-streaming or bidirectional-streaming RPC method."}], "cpeApplicability": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:elixir-grpc:grpc_server:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.0.6", "versionStartIncluding": "1.0.0", "vulnerable": true}], "negate": false, "operator": "OR"}], "operator": "AND"}], "credits": [{"lang": "en", "type": "finder", "value": "Arpit Jain"}, {"lang": "en", "type": "reporter", "value": "Arpit Jain"}, {"lang": "en", "type": "remediation developer", "value": "Arpit Jain"}, {"lang": "en", "type": "remediation reviewer", "value": "Paulo Valente"}, {"lang": "en", "type": "coordinator", "value": "Jonatan M\u00e4nnchen / EEF"}], "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>Allocation of Resources Without Limits or Throttling vulnerability in elixir-grpc grpc_server allows unauthenticated attackers to exhaust memory and crash the node via an oversized client-streaming or bidirectional-streaming request body.</p>\n<p>The streaming read clause of <code>'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3</code> (<code>grpc_server/lib/grpc/server/adapters/cowboy/handler.ex</code>) never checks the configured <code>max_body_size</code>. Only the unary read path enforces that cap. <code>'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1</code> (<code>grpc_server/lib/grpc/server/adapters/cowboy.ex</code>) appends every received chunk to its buffer until a complete length-prefixed message arrives. A client can declare a very large message and send it across many small HTTP/2 DATA frames, and the server buffers all of it.</p>\n<p>This issue affects grpc_server: from 1.0.0 before 1.0.6.</p>"}, {"base64": false, "type": "text/markdown", "value": "Allocation of Resources Without Limits or Throttling vulnerability in elixir-grpc grpc_server allows unauthenticated attackers to exhaust memory and crash the node via an oversized client-streaming or bidirectional-streaming request body.\n\nThe streaming read clause of `'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3` (`grpc_server/lib/grpc/server/adapters/cowboy/handler.ex`) never checks the configured `max_body_size`. Only the unary read path enforces that cap. `'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1` (`grpc_server/lib/grpc/server/adapters/cowboy.ex`) appends every received chunk to its buffer until a complete length-prefixed message arrives. A client can declare a very large message and send it across many small HTTP/2 DATA frames, and the server buffers all of it.\n\nThis issue affects grpc_server: from 1.0.0 before 1.0.6."}], "value": "Allocation of Resources Without Limits or Throttling vulnerability in elixir-grpc grpc_server allows unauthenticated attackers to exhaust memory and crash the node via an oversized client-streaming or bidirectional-streaming request body.\n\nThe streaming read clause of 'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3 (grpc_server/lib/grpc/server/adapters/cowboy/handler.ex) never checks the configured max_body_size. Only the unary read path enforces that cap. 'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1 (grpc_server/lib/grpc/server/adapters/cowboy.ex) appends every received chunk to its buffer until a complete length-prefixed message arrives. A client can declare a very large message and send it across many small HTTP/2 DATA frames, and the server buffers all of it.\n\nThis issue affects grpc_server: from 1.0.0 before 1.0.6."}], "impacts": [{"capecId": "CAPEC-130", "descriptions": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p>An unauthenticated client can crash a <code>grpc_server</code> node through one streaming RPC connection. This takes down every service on that node.</p>"}, {"base64": false, "type": "text/markdown", "value": "An unauthenticated client can crash a `grpc_server` node through one streaming RPC connection. This takes down every service on that node."}], "value": "An unauthenticated client can crash a grpc_server node through one streaming RPC connection. This takes down every service on that node."}]}], "metrics": [{"cvssV4_0": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "baseScore": 8.2, "baseSeverity": "HIGH", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "problemTypes": [{"descriptions": [{"cweId": "CWE-770", "description": "CWE-770 Allocation of Resources Without Limits or Throttling", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "shortName": "EEF", "dateUpdated": "2026-11-06T21:02:03.676Z"}, "references": [{"name": "Unbounded request body accumulation on streaming RPCs causes memory exhaustion in grpc_server", "tags": ["vendor-advisory", "related"], "url": "https://github.com/elixir-grpc/grpc/security/advisories/GHSA-vx6q-cr5q-945g"}, {"name": "EEF CNA record for CVE-2026-71397", "tags": ["related"], "url": "https://cna.erlef.org/cves/CVE-2026-71397.html"}, {"name": "OSV record EEF-CVE-2026-71397", "tags": ["related"], "url": "https://osv.dev/vulnerability/EEF-CVE-2026-71397"}, {"name": "Introducing commit 49e18c3 in elixir-grpc/grpc", "tags": ["related"], "url": "https://github.com/elixir-grpc/grpc/commit/49e18c3ec6bb9afe2f712caad3dbab5c56a68a00"}, {"name": "Fix commit 0b663ca in elixir-grpc/grpc", "tags": ["patch"], "url": "https://github.com/elixir-grpc/grpc/commit/0b663ca53dbf0f36f7f67ff1d0026f4482a18915"}], "source": {"discovery": "EXTERNAL"}, "title": "Unbounded request body accumulation on streaming RPCs causes memory exhaustion in grpc_server", "x_proofOfConcept": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<ol>\n<li>Start a <code>grpc_server</code> endpoint that exposes a client-streaming or bidirectional-streaming RPC method.</li>\n<li>Open an HTTP/2 connection and send a request to that method.</li>\n<li>Send the request body across many small HTTP/2 DATA frames without <code>END_STREAM</code>, well past the configured <code>max_body_size</code>.</li>\n<li>Observe that the server buffers all of it and server memory grows. The equivalent unary call is rejected with <code>RESOURCE_EXHAUSTED</code>.</li>\n</ol>"}, {"base64": false, "type": "text/markdown", "value": "1. Start a `grpc_server` endpoint that exposes a client-streaming or bidirectional-streaming RPC method.\n2. Open an HTTP/2 connection and send a request to that method.\n3. Send the request body across many small HTTP/2 DATA frames without `END_STREAM`, well past the configured `max_body_size`.\n4. Observe that the server buffers all of it and server memory grows. The equivalent unary call is rejected with `RESOURCE_EXHAUSTED`."}], "value": "* Start a grpc_server endpoint that exposes a client-streaming or bidirectional-streaming RPC method.\n* Open an HTTP/2 connection and send a request to that method.\n* Send the request body across many small HTTP/2 DATA frames without END_STREAM, well past the configured max_body_size.\n* Observe that the server buffers all of it and server memory grows. The equivalent unary call is rejected with RESOURCE_EXHAUSTED."}], "x_technicalAnalysis": [{"lang": "en", "supportingMedia": [{"base64": false, "type": "text/html", "value": "<p><strong>1. The cap applies to unary reads only</strong></p>\n<p>The commit that added <code>max_body_size</code> checks it in <code>read_full_body/4</code>, which serves unary requests through the <code>{:read_full_body, ref, pid}</code> clause of <code>'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3</code>. The <code>{:read_body, ref, pid}</code> clause, which serves streaming requests, returns each chunk to the caller with no size check.</p>\n<p><strong>2. Unbounded buffering</strong></p>\n<p><code>'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1</code> reads chunks through that clause and appends each one to a binary buffer. It emits a message only when <code>GRPC.Message.get_message/1</code> finds a complete length-prefixed gRPC message in the buffer. Until then, the buffer grows with every chunk.</p>\n<p><strong>3. Memory exhaustion</strong></p>\n<p>A client that declares a large message length and keeps sending DATA frames without <code>END_STREAM</code> makes the buffer grow without limit. The BEAM eventually runs out of memory and the node crashes.</p>"}, {"base64": false, "type": "text/markdown", "value": "**1. The cap applies to unary reads only**\n\nThe commit that added `max_body_size` checks it in `read_full_body/4`, which serves unary requests through the `{:read_full_body, ref, pid}` clause of `'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3`. The `{:read_body, ref, pid}` clause, which serves streaming requests, returns each chunk to the caller with no size check.\n\n**2. Unbounded buffering**\n\n`'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1` reads chunks through that clause and appends each one to a binary buffer. It emits a message only when `GRPC.Message.get_message/1` finds a complete length-prefixed gRPC message in the buffer. Until then, the buffer grows with every chunk.\n\n**3. Memory exhaustion**\n\nA client that declares a large message length and keeps sending DATA frames without `END_STREAM` makes the buffer grow without limit. The BEAM eventually runs out of memory and the node crashes."}], "value": "1. The cap applies to unary reads only\n\nThe commit that added max_body_size checks it in read_full_body/4, which serves unary requests through the {:read_full_body, ref, pid} clause of 'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3. The {:read_body, ref, pid} clause, which serves streaming requests, returns each chunk to the caller with no size check.\n\n2. Unbounded buffering\n\n'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1 reads chunks through that clause and appends each one to a binary buffer. It emits a message only when GRPC.Message.get_message/1 finds a complete length-prefixed gRPC message in the buffer. Until then, the buffer grows with every chunk.\n\n3. Memory exhaustion\n\nA client that declares a large message length and keeps sending DATA frames without END_STREAM makes the buffer grow without limit. The BEAM eventually runs out of memory and the node crashes."}]}}}

{}

{"affected": [{"affectedData": [{"collectionURL": "https://repo.hex.pm", "cpes": ["cpe:2.3:a:elixir-grpc:grpc_server:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.GRPC.Server.Adapters.Cowboy.Handler'", "'Elixir.GRPC.Server.Adapters.Cowboy'"], "packageName": "grpc_server", "packageURL": "pkg:hex/grpc_server", "product": "grpc_server", "programFiles": ["lib/grpc/server/adapters/cowboy/handler.ex", "lib/grpc/server/adapters/cowboy.ex"], "programRoutines": [{"name": "'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3"}, {"name": "'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1"}], "repo": "https://github.com/elixir-grpc/grpc", "vendor": "elixir-grpc", "versions": [{"lessThan": "1.0.6", "status": "affected", "version": "1.0.0", "versionType": "semver"}]}, {"collectionURL": "https://github.com", "cpes": ["cpe:2.3:a:elixir-grpc:grpc_server:*:*:*:*:*:*:*:*"], "defaultStatus": "unaffected", "modules": ["'Elixir.GRPC.Server.Adapters.Cowboy.Handler'", "'Elixir.GRPC.Server.Adapters.Cowboy'"], "packageName": "elixir-grpc/grpc", "packageURL": "pkg:github/elixir-grpc/grpc", "product": "grpc_server", "programFiles": ["grpc_server/lib/grpc/server/adapters/cowboy/handler.ex", "grpc_server/lib/grpc/server/adapters/cowboy.ex"], "programRoutines": [{"name": "'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3"}, {"name": "'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1"}], "repo": "https://github.com/elixir-grpc/grpc", "vendor": "elixir-grpc", "versions": [{"lessThan": "0b663ca53dbf0f36f7f67ff1d0026f4482a18915", "status": "affected", "version": "49e18c3ec6bb9afe2f712caad3dbab5c56a68a00", "versionType": "git"}]}], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Allocation of Resources Without Limits or Throttling vulnerability in elixir-grpc grpc_server allows unauthenticated attackers to exhaust memory and crash the node via an oversized client-streaming or bidirectional-streaming request body.\n\nThe streaming read clause of 'Elixir.GRPC.Server.Adapters.Cowboy.Handler':info/3 (grpc_server/lib/grpc/server/adapters/cowboy/handler.ex) never checks the configured max_body_size. Only the unary read path enforces that cap. 'Elixir.GRPC.Server.Adapters.Cowboy':reading_stream/1 (grpc_server/lib/grpc/server/adapters/cowboy.ex) appends every received chunk to its buffer until a complete length-prefixed message arrives. A client can declare a very large message and send it across many small HTTP/2 DATA frames, and the server buffers all of it.\n\nThis issue affects grpc_server: from 1.0.0 before 1.0.6."}], "id": "CVE-2026-71397", "lastModified": "2026-11-06T21:17:10.480", "metrics": {"cvssMetricV40": [{"cvssData": {"Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "Safety": "NOT_DEFINED", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "attackVector": "NETWORK", "availabilityRequirement": "NOT_DEFINED", "baseScore": 8.2, "baseSeverity": "HIGH", "confidentialityRequirement": "NOT_DEFINED", "exploitMaturity": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "privilegesRequired": "NONE", "providerUrgency": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "userInteraction": "NONE", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/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", "version": "4.0", "vulnAvailabilityImpact": "HIGH", "vulnConfidentialityImpact": "NONE", "vulnIntegrityImpact": "NONE", "vulnerabilityResponseEffort": "NOT_DEFINED"}, "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary"}]}, "published": "2026-11-06T21:17:10.480", "references": [{"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://cna.erlef.org/cves/CVE-2026-71397.html"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/elixir-grpc/grpc/commit/0b663ca53dbf0f36f7f67ff1d0026f4482a18915"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/elixir-grpc/grpc/commit/49e18c3ec6bb9afe2f712caad3dbab5c56a68a00"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://github.com/elixir-grpc/grpc/security/advisories/GHSA-vx6q-cr5q-945g"}, {"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "url": "https://osv.dev/vulnerability/EEF-CVE-2026-71397"}], "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-770"}], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "type": "Secondary"}]}

{}

{}