CVE-2026-56811

{"id": "CVE-2026-56811", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-56811", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-07-07T16:12:27.662417Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}], "cvssMetricV40": [{"type": "Secondary", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 8.7, "Automatable": "NOT_DEFINED", "attackVector": "NETWORK", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "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", "exploitMaturity": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "userInteraction": "NONE", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "NONE", "subIntegrityImpact": "NONE", "vulnIntegrityImpact": "NONE", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "NONE", "confidentialityRequirement": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED"}}]}, "affected": [{"source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "affectedData": [{"cpes": ["cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*"], "repo": "https://github.com/phoenixframework/phoenix", "vendor": "phoenixframework", "modules": ["'Elixir.Phoenix.Socket'"], "product": "phoenix", "versions": [{"status": "affected", "version": "0.11.0", "lessThan": "1.5.15", "versionType": "semver"}, {"status": "affected", "version": "1.6.0-rc.0", "lessThan": "1.6.17", "versionType": "semver"}, {"status": "affected", "version": "1.7.0-rc.0", "lessThan": "1.7.24", "versionType": "semver"}, {"status": "affected", "version": "1.8.0-rc.0", "lessThan": "1.8.9", "versionType": "semver"}], "packageURL": "pkg:hex/phoenix", "packageName": "phoenix", "programFiles": ["lib/phoenix/socket.ex"], "collectionURL": "https://repo.hex.pm", "defaultStatus": "unaffected", "programRoutines": [{"name": "'Elixir.Phoenix.Socket':handle_in/4"}]}, {"cpes": ["cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*"], "repo": "https://github.com/phoenixframework/phoenix", "vendor": "phoenixframework", "modules": ["'Elixir.Phoenix.Socket'"], "product": "phoenix", "versions": [{"status": "affected", "changes": [{"at": "c498ba8cf49f6accbbd0c643a5340b58db891218", "status": "unaffected"}, {"at": "d19ca0a8d9f82c130b7ed339b9f033433e2dea5e", "status": "unaffected"}, {"at": "a612100cd8a4279091abc1a2ef8fb98a6d01c0a1", "status": "unaffected"}, {"at": "16e295d2fccab185d1292322e2bee5d46c725c8a", "status": "unaffected"}], "version": "14a297e88023cb280a577962a49a0bbdeef9f4eb", "lessThan": "*", "versionType": "git"}], "packageURL": "pkg:github/phoenixframework/phoenix", "packageName": "phoenixframework/phoenix", "programFiles": ["lib/phoenix/socket.ex"], "collectionURL": "https://github.com", "defaultStatus": "unaffected", "programRoutines": [{"name": "'Elixir.Phoenix.Socket':handle_in/4"}]}]}], "published": "2026-07-07T16:16:40.710", "references": [{"url": "https://cna.erlef.org/cves/CVE-2026-56811.html", "tags": ["Mitigation", "Patch", "Third Party Advisory"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/phoenixframework/phoenix/commit/14a297e88023cb280a577962a49a0bbdeef9f4eb", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/phoenixframework/phoenix/commit/16e295d2fccab185d1292322e2bee5d46c725c8a", "tags": ["Patch"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/phoenixframework/phoenix/commit/a612100cd8a4279091abc1a2ef8fb98a6d01c0a1", "tags": ["Patch"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/phoenixframework/phoenix/commit/c498ba8cf49f6accbbd0c643a5340b58db891218", "tags": ["Patch"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/phoenixframework/phoenix/commit/d19ca0a8d9f82c130b7ed339b9f033433e2dea5e", "tags": ["Patch"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/phoenixframework/phoenix/security/advisories/GHSA-6983-jfq8-485w", "tags": ["Patch", "Vendor Advisory"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://osv.dev/vulnerability/EEF-CVE-2026-56811", "tags": ["Mitigation", "Third Party Advisory"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Secondary", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "description": [{"lang": "en", "value": "CWE-770"}]}], "descriptions": [{"lang": "en", "value": "Allocation of Resources Without Limits or Throttling vulnerability in phoenixframework phoenix (Phoenix.Socket module) allows an unauthenticated attacker to cause a denial of service against any endpoint that mounts a Phoenix socket with a reachable channel transport (WebSocket or LongPoll).\n\nThis vulnerability is associated with program files lib/phoenix/socket.ex and program routine 'Elixir.Phoenix.Socket':handle_in/4.\n\nPhoenix transports do not limit the number of channels that a single transport process may join. Every phx_join message a client sends over one connection starts a persistent channel process, and the socket process accepts an unbounded number of them. A single unauthenticated client can therefore open one WebSocket or LongPoll connection and stream a large number of phx_join messages, spawning hundreds of thousands of channel processes over that one connection and eventually reaching the BEAM maximum process limit. Once the process table is exhausted the virtual machine can no longer start new processes, denying service to legitimate traffic across the whole node. Because the amplification happens inside a single connection, network-layer connection caps and rate limiting do not mitigate it.\n\nThe fix adds a :max_channels_per_transport option (default 100) that bounds the number of channels a single transport process can join, forcing abusive clients to open many connections instead, where external load balancers and reverse proxies can throttle them.\n\nThis issue affects phoenix: from 0.11.0 before 1.5.15, from 1.6.0-rc.0 before 1.6.17, from 1.7.0-rc.0 before 1.7.24, and from 1.8.0-rc.0 before 1.8.9."}, {"lang": "es", "value": "La vulnerabilidad de asignaci\u00f3n de recursos sin l\u00edmites ni estrangulamiento en phoenixframework phoenix (m\u00f3dulo Phoenix.Socket) permite a un atacante no autenticado causar una denegaci\u00f3n de servicio contra cualquier punto final que monte un socket Phoenix con un transporte de canal accesible (WebSocket o LongPoll).\n\nEsta vulnerabilidad est\u00e1 asociada con los archivos de programa lib/phoenix/socket.ex y la rutina de programa \u2019Elixir.Phoenix.Socket\u2019:handle_in/4.\n\nLos transportes de Phoenix no limitan el n\u00famero de canales a los que puede unirse un \u00fanico proceso de transporte. Cada mensaje phx_join que un cliente env\u00eda a trav\u00e9s de una conexi\u00f3n inicia un proceso de canal persistente, y el proceso de socket acepta un n\u00famero ilimitado de ellos. Por lo tanto, un \u00fanico cliente no autenticado puede abrir una conexi\u00f3n WebSocket o LongPoll y transmitir un gran n\u00famero de mensajes phx_join, generando cientos de miles de procesos de canal a trav\u00e9s de esa \u00fanica conexi\u00f3n y finalmente alcanzando el l\u00edmite m\u00e1ximo de procesos de BEAM. Una vez que la tabla de procesos se agota, la m\u00e1quina virtual ya no puede iniciar nuevos procesos, denegando el servicio al tr\u00e1fico leg\u00edtimo en todo el nodo. Debido a que la amplificaci\u00f3n ocurre dentro de una \u00fanica conexi\u00f3n, los l\u00edmites de conexi\u00f3n de la capa de red y la limitaci\u00f3n de velocidad no lo mitigan.\n\nLa soluci\u00f3n a\u00f1ade una opci\u00f3n :max_channels_per_transport (por defecto 100) que limita el n\u00famero de canales a los que puede unirse un \u00fanico proceso de transporte, obligando a los clientes abusivos a abrir muchas conexiones en su lugar, donde los balanceadores de carga externos y los proxies inversos pueden estrangularlos.\n\nEste problema afecta a phoenix: desde 0.11.0 antes de 1.5.15, desde 1.6.0-rc.0 antes de 1.6.17, desde 1.7.0-rc.0 antes de 1.7.24, y desde 1.8.0-rc.0 antes de 1.8.9."}], "lastModified": "2026-10-25T20:10:00.147", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "3CF8EA55-C063-4742-87ED-53E1998977B5", "versionEndExcluding": "1.5.15", "versionStartIncluding": "1.2.0"}, {"criteria": "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "809E49A8-D727-4E05-BBF9-F9E34077E4A4", "versionEndExcluding": "1.6.17", "versionStartIncluding": "1.6.0"}, {"criteria": "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "3257C901-8FC3-4107-95C6-C57F909FFE40", "versionEndExcluding": "1.7.24", "versionStartIncluding": "1.7.0"}, {"criteria": "cpe:2.3:a:phoenixframework:phoenix:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "8F98C1AC-1593-43EB-929A-4D3B7597C9BC", "versionEndExcluding": "1.8.9", "versionStartIncluding": "1.8.0"}], "operator": "OR"}]}], "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}