CVE-2026-74755

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The UnparsedValue::as_string() function computes `_size - 1` without validating `_size`; when value_size is 0 the expression underflows to SIZE_MAX, resize() throws std::length_error, and because the exception is not caught on the request parsing path the process aborts (SIGABRT).\n\nRoot Cause:\nIn src/mcpack2pb/parser.cpp, UnparsedValue::as_string() resizes the output string to `_size - 1`, where `_size` is the value_size of a string field taken directly from the network data. A value_size of 0 underflows the unsigned size_t, and the subsequent resize() throws an exception that is not caught.\n\nAffected Scenarios:\nbRPC servers that accept nshead frames wired to the ubrpc mcpack2 adaptor (for example the NsheadService + UbrpcMcpack2Adaptor deployment pattern) can be crashed by a single unauthenticated request. Stock open-source bRPC registers the ubrpc/nshead_mcpack protocols as client-only, so default server configurations are not affected.\n\nHow to Fix:\n1. Upgrade bRPC to a version that includes this fix.\n2. Apply the patch in PR\u00a0 https://github.com/apache/brpc/pull/3450", "lang": "en", "supportingMedia": [{"type": "text/html", "base64": false, "value": "An integer underflow in the mcpack2pb component of Apache bRPC (version &lt; 1.18.0) on all platforms allows remote attackers to crash a bRPC server by sending a request containing a string field with a zero value_size. The UnparsedValue::as_string() function computes `_size - 1` without validating `_size`; when value_size is 0 the expression underflows to SIZE_MAX, resize() throws std::length_error, and because the exception is not caught on the request parsing path the process aborts (SIGABRT).<br><br>Root Cause:<br>In src/mcpack2pb/parser.cpp, UnparsedValue::as_string() resizes the output string to `_size - 1`, where `_size` is the value_size of a string field taken directly from the network data. A value_size of 0 underflows the unsigned size_t, and the subsequent resize() throws an exception that is not caught.<br><br>Affected Scenarios:<br>bRPC servers that accept nshead frames wired to the ubrpc mcpack2 adaptor (for example the NsheadService + UbrpcMcpack2Adaptor deployment pattern) can be crashed by a single unauthenticated request. Stock open-source bRPC registers the ubrpc/nshead_mcpack protocols as client-only, so default server configurations are not affected.<br><br>How to Fix:<br>1. Upgrade bRPC to a version that includes this fix.<br>2. Apply the patch in PR&nbsp;<a target=\"_blank\" rel=\"nofollow\" href=\"https://github.com/apache/brpc/pull/3450\">https://github.com/apache/brpc/pull/3450</a>&nbsp;"}]}], "references": [{"url": "https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb", "tags": ["vendor-advisory"]}], "metrics": [{"other": {"type": "Textual description of severity", "content": {"text": "moderate"}}, "scenarios": [{"lang": "en", "value": "GENERAL"}]}], "credits": [{"lang": "en", "value": "Feng Zhijie (Independent security researcher)", "type": "finder"}], "x_generator": {"engine": "Vulnogram 0.2.0"}}, "adp": [{"metrics": [{"cvssV3_1": {"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"}}, {"other": {"type": "ssvc", "content": {"timestamp": "2026-10-30T17:56:37.339174Z", "id": "CVE-2026-74755", "options": [{"Exploitation": "none"}, {"Automatable": "yes"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-30T17:56:42.592Z"}}]}}

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Upgrade bRPC to a version that includes this fix.\n2. Apply the patch in PR\u00a0 https://github.com/apache/brpc/pull/3450", "supportingMedia": [{"type": "text/html", "value": "An integer underflow in the mcpack2pb component of Apache bRPC (version &lt; 1.18.0) on all platforms allows remote attackers to crash a bRPC server by sending a request containing a string field with a zero value_size. The UnparsedValue::as_string() function computes `_size - 1` without validating `_size`; when value_size is 0 the expression underflows to SIZE_MAX, resize() throws std::length_error, and because the exception is not caught on the request parsing path the process aborts (SIGABRT).<br><br>Root Cause:<br>In src/mcpack2pb/parser.cpp, UnparsedValue::as_string() resizes the output string to `_size - 1`, where `_size` is the value_size of a string field taken directly from the network data. A value_size of 0 underflows the unsigned size_t, and the subsequent resize() throws an exception that is not caught.<br><br>Affected Scenarios:<br>bRPC servers that accept nshead frames wired to the ubrpc mcpack2 adaptor (for example the NsheadService + UbrpcMcpack2Adaptor deployment pattern) can be crashed by a single unauthenticated request. Stock open-source bRPC registers the ubrpc/nshead_mcpack protocols as client-only, so default server configurations are not affected.<br><br>How to Fix:<br>1. Upgrade bRPC to a version that includes this fix.<br>2. 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{"affected": [{"affectedData": [{"collectionURL": "https://github.com", "defaultStatus": "unaffected", "packageName": "apache/brpc", "packageURL": "pkg:github/apache/brpc", "product": "Apache bRPC", "vendor": "Apache Software Foundation", "versions": [{"lessThan": "1.18.0", "status": "affected", "version": "0", "versionType": "semver"}]}], "source": "security@apache.org"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "An integer underflow in the mcpack2pb component of Apache bRPC (version < 1.18.0) on all platforms allows remote attackers to crash a bRPC server by sending a request containing a string field with a zero value_size. The UnparsedValue::as_string() function computes `_size - 1` without validating `_size`; when value_size is 0 the expression underflows to SIZE_MAX, resize() throws std::length_error, and because the exception is not caught on the request parsing path the process aborts (SIGABRT).\n\nRoot Cause:\nIn src/mcpack2pb/parser.cpp, UnparsedValue::as_string() resizes the output string to `_size - 1`, where `_size` is the value_size of a string field taken directly from the network data. A value_size of 0 underflows the unsigned size_t, and the subsequent resize() throws an exception that is not caught.\n\nAffected Scenarios:\nbRPC servers that accept nshead frames wired to the ubrpc mcpack2 adaptor (for example the NsheadService + UbrpcMcpack2Adaptor deployment pattern) can be crashed by a single unauthenticated request. Stock open-source bRPC registers the ubrpc/nshead_mcpack protocols as client-only, so default server configurations are not affected.\n\nHow to Fix:\n1. Upgrade bRPC to a version that includes this fix.\n2. Apply the patch in PR\u00a0 https://github.com/apache/brpc/pull/3450"}, {"lang": "es", "value": "Una vulnerabilidad de desbordamiento por entero en el componente mcpack2pb de Apache bRPC (versi\u00f3n anterior a la 1.18.0) en todas las plataformas permite a atacantes remotos bloquear un servidor bRPC enviando una solicitud que contiene un campo de cadena con un value_size igual a cero. La funci\u00f3n UnparsedValue::as_string() calcula \u201c_size - 1\u201d sin validar \u201c_size\u201d; cuando value_size es 0 la expresi\u00f3n desborda a SIZE_MAX, resize() lanza std::length_error y, como la excepci\u00f3n no se captura en la ruta de an\u00e1lisis de la solicitud, el proceso aborta (SIGABRT).\\n\\nCausa ra\u00edz:\\nEn src/mcpack2pb/parser.cpp, UnparsedValue::as_string() redimensiona la cadena de salida a \u201c_size - 1\u201d, donde \u201c_size\u201d es el value_size de un campo de cadena tomado directamente de los datos de la red. Un value_size de 0 desborda el size_t sin signo, y el posterior resize() lanza una excepci\u00f3n que no se captura.\\n\\nEscenarios afectados:\\nLos servidores bRPC que aceptan tramas nshead conectadas al adaptador ubrpc mcpack2 (por ejemplo, el patr\u00f3n de despliegue NsheadService + UbrpcMcpack2Adaptor) pueden ser bloqueados por una \u00fanica solicitud no autenticada. La versi\u00f3n de c\u00f3digo abierto de bRPC registra los protocolos ubrpc/nshead_mcpack como solo cliente, por lo que las configuraciones de servidor predeterminadas no se ven afectadas.\\n\\nC\u00f3mo corregir:\\n1. Actualizar bRPC a una versi\u00f3n que incluya esta correcci\u00f3n. \\n2. Aplicar el parche en PR\u00a0https://github.com/apache/brpc/pull/3450"}], "id": "CVE-2026-74755", "lastModified": "2026-10-30T18:18:12.603", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-74755", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-10-30T17:56:37.339174Z", "version": "2.0.3"}}]}, "published": "2026-10-21T12:17:22.550", "references": [{"source": "security@apache.org", "url": "https://lists.apache.org/thread/2pf15ojj0vr7rtx95677kgtl1mx3gdgb"}], "sourceIdentifier": "security@apache.org", "vulnStatus": "Deferred", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-191"}], "source": "security@apache.org", "type": "Secondary"}]}

{}

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