CVE-2026-55950

{"id": "CVE-2026-55950", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-55950", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-07-02T17:25:47.169172Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.9, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 2.2}], "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:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "modules": ["dtls_packet_demux"], "product": "OTP", "versions": [{"status": "affected", "changes": [{"at": "11.7.3", "status": "unaffected"}, {"at": "11.6.0.3", "status": "unaffected"}, {"at": "11.2.12.10", "status": "unaffected"}], "version": "10.9", "lessThan": "*", "versionType": "otp"}], "packageURL": "pkg:otp/ssl?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git", "packageName": "ssl", "programFiles": ["src/dtls_packet_demux.erl"], "defaultStatus": "unaffected", "programRoutines": [{"name": "dtls_packet_demux:handle_call/3"}, {"name": "dtls_packet_demux:handle_info/2"}, {"name": "dtls_packet_demux:new_connection/2"}]}, {"cpes": ["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"], "repo": "https://github.com/erlang/otp", "vendor": "Erlang", "modules": ["dtls_packet_demux"], "product": "OTP", "versions": [{"status": "affected", "changes": [{"at": "29.0.3", "status": "unaffected"}, {"at": "28.5.0.3", "status": "unaffected"}, {"at": "27.3.4.14", "status": "unaffected"}], "version": "25.3", "lessThan": "*", "versionType": "otp"}, {"status": "affected", "version": "44dcb4c3d900777493ce2a6129f451aa475811f9", "lessThan": "e44d2bf01c4473ef2ea7f09e3523cf96de6e4a04", "versionType": "git"}], "packageURL": "pkg:github/erlang/otp", "packageName": "erlang/otp", "programFiles": ["lib/ssl/src/dtls_packet_demux.erl"], "collectionURL": "https://github.com", "defaultStatus": "unaffected", "programRoutines": [{"name": "dtls_packet_demux:handle_call/3"}, {"name": "dtls_packet_demux:handle_info/2"}, {"name": "dtls_packet_demux:new_connection/2"}]}]}], "published": "2026-07-02T17:17:02.910", "references": [{"url": "https://cna.erlef.org/cves/CVE-2026-55950.html", "tags": ["Vendor Advisory"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/erlang/otp/commit/e44d2bf01c4473ef2ea7f09e3523cf96de6e4a04", "tags": ["Patch"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://github.com/erlang/otp/security/advisories/GHSA-hwfc-5hf4-gvr3", "tags": ["Vendor Advisory"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://osv.dev/vulnerability/EEF-CVE-2026-55950", "tags": ["Third Party Advisory"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}, {"url": "https://www.erlang.org/doc/system/versions.html#order-of-versions", "tags": ["Release Notes"], "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Secondary", "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db", "description": [{"lang": "en", "value": "CWE-367"}]}], "descriptions": [{"lang": "en", "value": "Time-of-check Time-of-use (TOCTOU) race condition vulnerability in Erlang/OTP ssl (dtls_packet_demux module) allows an unauthenticated remote attacker to crash all active DTLS sessions on a listener.\n\nA DTLS server listener uses a single shared dtls_packet_demux gen_server process to route incoming UDP datagrams to the correct connection handler. When a DTLS client reconnects rapidly from the same source address and port (sending multiple ClientHello messages in quick succession), a race condition in the demux's internal gb_trees key-value store causes a {key_exists, {old, Client}} crash, terminating the demux process. Because the demux is shared across all DTLS associations on that listener, its crash immediately kills every active DTLS session, not just the attacker's.\n\nThe attack is pre-authentication: the attacker only needs to send UDP datagrams containing valid ClientHello messages from the same source IP and port before the intermediate DOWN monitor message is processed by the gen_server. No credentials, no completed handshake, and no special configuration are required, and the crash can be repeated indefinitely to create a persistent denial of service for all clients of that listener.\n\nThis vulnerability is associated with program file lib/ssl/src/dtls_packet_demux.erl.\n\nThis issue affects OTP from OTP 25.3 before OTP\u00a029.0.3, OTP\u00a028.5.0.3 and OTP\u00a027.3.4.14, corresponding to ssl from 10.9 before 11.7.3, 11.6.0.3 and 11.2.12.10."}, {"lang": "es", "value": "Vulnerabilidad de condici\u00f3n de carrera Time-of-check Time-of-use (TOCTOU) en Erlang/OTP ssl (m\u00f3dulo dtls_packet_demux) permite a un atacante remoto no autenticado colapsar todas las sesiones DTLS activas en un oyente.\n\nUn oyente de servidor DTLS utiliza un \u00fanico proceso gen_server dtls_packet_demux compartido para enrutar datagramas UDP entrantes al gestor de conexi\u00f3n correcto. Cuando un cliente DTLS se reconecta r\u00e1pidamente desde la misma direcci\u00f3n de origen y puerto (enviando m\u00faltiples mensajes ClientHello en r\u00e1pida sucesi\u00f3n), una condici\u00f3n de carrera en el almac\u00e9n clave-valor gb_trees interno del demux causa un colapso {key_exists, {old, Client}}, terminando el proceso demux. Debido a que el demux se comparte entre todas las asociaciones DTLS en ese oyente, su colapso mata inmediatamente cada sesi\u00f3n DTLS activa, no solo la del atacante.\n\nEl ataque es de pre-autenticaci\u00f3n: el atacante solo necesita enviar datagramas UDP que contengan mensajes ClientHello v\u00e1lidos desde la misma IP de origen y puerto antes de que el mensaje de monitor DOWN intermedio sea procesado por el gen_server. No se requieren credenciales, ni un handshake completado, ni una configuraci\u00f3n especial, y el colapso puede repetirse indefinidamente para crear una denegaci\u00f3n de servicio persistente para todos los clientes de ese oyente.\n\nEsta vulnerabilidad est\u00e1 asociada con el archivo de programa lib/ssl/src/dtls_packet_demux.erl.\n\nEste problema afecta a OTP desde OTP 25.3 antes de 29.0.3, 28.5.0.3 y 27.3.4.14 correspondiente a ssl desde 10.9 antes de 11.7.3, 11.6.0.3 y 11.2.12.10."}], "lastModified": "2026-10-25T21:10:00.770", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6C582A53-04F6-4606-9FC5-191C948E4890", "versionEndExcluding": "27.3.4.14", "versionStartIncluding": "25.3"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "230E3EE3-6A18-4848-8E3D-DB0FAA8EDFDC", "versionEndExcluding": "28.5.0.3", "versionStartIncluding": "28.0"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "5D2D0C24-E302-48BF-9550-CCC7ABA24BED", "versionEndExcluding": "29.0.3", "versionStartIncluding": "29.0"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/ssl:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B28E54A4-DCFD-4B62-A526-8A3EEE07B3F5", "versionEndExcluding": "11.2.12.10", "versionStartIncluding": "10.9"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/ssl:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "670E1622-32D4-45D0-A05E-9A3F76CC0F15", "versionEndExcluding": "11.6.0.3", "versionStartIncluding": "11.3"}, {"criteria": "cpe:2.3:a:erlang:erlang\\/ssl:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "217D7CA5-49E9-4805-A2F6-32EC75F6EE91", "versionEndExcluding": "11.7.3", "versionStartIncluding": "11.7"}], "operator": "OR"}]}], "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}