CVE-2025-64076

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{"affected": [{"affectedData": [{"product": "n/a", "vendor": "n/a", "versions": [{"status": "affected", "version": "n/a"}]}], "source": "cve@mitre.org"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:agronholm:cbor2:*:*:*:*:*:python:*:*", "matchCriteriaId": "AE04A1BB-A030-4607-9B76-8CFEC625F070", "versionEndIncluding": "5.7.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Multiple vulnerabilities exist in cbor2 through version 5.7.0 in the decode_definite_long_string() function of the C extension decoder (source/decoder.c): (1) Integer Underflow Leading to Out-of-Bounds Read (CWE-191, CWE-125): An incorrect variable reference and missing state reset in the chunk processing loop causes buffer_length to not be reset to zero after UTF-8 character consumption. This results in subsequent chunk_length calculations producing negative values (e.g., chunk_length = 65536 - buffer_length), which are passed as signed integers to the read() method, potentially triggering unlimited read operations and resource exhaustion. (2) Memory Leak via Missing Reference Count Release (CWE-401): The main processing loop fails to release Python object references (Py_DECREF) for chunk objects allocated in each iteration. For CBOR strings longer than 65536 bytes, this causes cumulative memory leaks proportional to the payload size, enabling memory exhaustion attacks through repeated processing of large CBOR payloads. Both vulnerabilities can be exploited remotely without authentication by sending specially-crafted CBOR data containing definite-length text strings with multi-byte UTF-8 characters positioned at 65536-byte chunk boundaries. Successful exploitation results in denial of service through process crashes (CBORDecodeEOF exceptions) or memory exhaustion. The vulnerabilities affect all applications using cbor2's C extension to process untrusted CBOR data, including web APIs, IoT data collectors, and message queue processors. Fixed in commit 851473490281f82d82560b2368284ef33cf6e8f9 pushed with released version 5.7.1."}, {"lang": "es", "value": "M\u00faltiples vulnerabilidades existen en cbor2 hasta la versi\u00f3n 5.7.0 en la funci\u00f3n decode_definite_long_string() del decodificador de la extensi\u00f3n C (source/decoder.c): (1) Desbordamiento negativo de enteros (Integer Underflow) que conduce a lectura fuera de l\u00edmites (Out-of-Bounds Read) (CWE-191, CWE-125): Una referencia de variable incorrecta y una falta de reinicio de estado en el bucle de procesamiento de fragmentos hacen que buffer_length no se reinicie a cero despu\u00e9s del consumo de caracteres UTF-8. Esto resulta en que los c\u00e1lculos subsiguientes de chunk_length produzcan valores negativos (p. ej., chunk_length = 65536 - buffer_length), los cuales se pasan como enteros con signo al m\u00e9todo read(), lo que podr\u00eda desencadenar operaciones de lectura ilimitadas y agotamiento de recursos. (2) Fuga de memoria por falta de liberaci\u00f3n del contador de referencias (Memory Leak via Missing Reference Count Release) (CWE-401): El bucle de procesamiento principal no libera referencias de objetos Python (Py_DECREF) para los objetos de fragmento asignados en cada iteraci\u00f3n. Para cadenas CBOR de m\u00e1s de 65536 bytes, esto causa fugas de memoria acumulativas proporcionales al tama\u00f1o de la carga \u00fatil, lo que permite ataques de agotamiento de memoria mediante el procesamiento repetido de grandes cargas \u00fatiles CBOR. Ambas vulnerabilidades pueden ser explotadas remotamente sin autenticaci\u00f3n enviando datos CBOR especialmente dise\u00f1ados que contengan cadenas de texto de longitud definida con caracteres UTF-8 multibyte posicionados en los l\u00edmites de fragmentos de 65536 bytes. La explotaci\u00f3n exitosa resulta en denegaci\u00f3n de servicio a trav\u00e9s de fallos de proceso (excepciones CBORDecodeEOF) o agotamiento de memoria. Las vulnerabilidades afectan a todas las aplicaciones que utilizan la extensi\u00f3n C de cbor2 para procesar datos CBOR no confiables, incluyendo APIs web, recolectores de datos IoT y procesadores de colas de mensajes. Corregido en el commit 851473490281f82d82560b2368284ef33cf6e8f9 publicado con la versi\u00f3n 5.7.1."}], "id": "CVE-2025-64076", "lastModified": "2026-11-05T14:10:00.273", "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": "cve@mitre.org", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2025-64076", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2025-11-19T13:54:52.352278Z", "version": "2.0.3"}}]}, "published": "2025-11-18T18:16:14.263", "references": [{"source": "cve@mitre.org", "tags": ["Patch"], "url": "https://github.com/agronholm/cbor2/commit/851473490281f82d82560b2368284ef33cf6e8f9"}, {"source": "cve@mitre.org", "tags": ["Exploit", "Issue Tracking"], "url": "https://github.com/agronholm/cbor2/issues/264"}, {"source": "cve@mitre.org", "tags": ["Exploit", "Issue Tracking", "Patch"], "url": "https://github.com/agronholm/cbor2/pull/265"}], "sourceIdentifier": "cve@mitre.org", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-191"}], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary"}]}

{"bugzilla": {"description": "cbor2: cbor2: Integer Underflow and Memory Leak leading to Denial of Service", "id": "2415716", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2415716"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-191", "details": ["Multiple vulnerabilities exist in cbor2 through version 5.7.0 in the decode_definite_long_string() function of the C extension decoder (source/decoder.c): (1) Integer Underflow Leading to Out-of-Bounds Read (CWE-191, CWE-125): An incorrect variable reference and missing state reset in the chunk processing loop causes buffer_length to not be reset to zero after UTF-8 character consumption. This results in subsequent chunk_length calculations producing negative values (e.g., chunk_length = 65536 - buffer_length), which are passed as signed integers to the read() method, potentially triggering unlimited read operations and resource exhaustion. (2) Memory Leak via Missing Reference Count Release (CWE-401): The main processing loop fails to release Python object references (Py_DECREF) for chunk objects allocated in each iteration. For CBOR strings longer than 65536 bytes, this causes cumulative memory leaks proportional to the payload size, enabling memory exhaustion attacks through repeated processing of large CBOR payloads. Both vulnerabilities can be exploited remotely without authentication by sending specially-crafted CBOR data containing definite-length text strings with multi-byte UTF-8 characters positioned at 65536-byte chunk boundaries. Successful exploitation results in denial of service through process crashes (CBORDecodeEOF exceptions) or memory exhaustion. The vulnerabilities affect all applications using cbor2's C extension to process untrusted CBOR data, including web APIs, IoT data collectors, and message queue processors. Fixed in commit 851473490281f82d82560b2368284ef33cf6e8f9 pushed with released version 5.7.1.", "A flaw was found in cbor2. This vulnerability allows denial of service through process crashes or memory exhaustion via sending specially-crafted CBOR data containing definite-length text strings with multi-byte UTF-8 characters."], "name": "CVE-2025-64076", "public_date": "2025-11-18T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-64076\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-64076\nhttps://github.com/agronholm/cbor2/commit/851473490281f82d82560b2368284ef33cf6e8f9\nhttps://github.com/agronholm/cbor2/issues/264\nhttps://github.com/agronholm/cbor2/pull/265"], "statement": "This flaw is marked IMPORTANT because the highest threat of this flaw is to system availability, as successful exploitation can lead to denial of service through process crashes or memory exhaustion.", "threat_severity": "Important"}

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