CVE-2026-12259

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{"affected": [{"affectedData": [{"product": "nltk/nltk", "vendor": "nltk", "versions": [{"lessThanOrEqual": "latest", "status": "affected", "version": "unspecified", "versionType": "custom"}]}], "source": "security@huntr.dev"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:nltk:nltk:3.9.4:*:*:*:*:*:*:*", "matchCriteriaId": "E0F7C7D0-ADBA-409B-9E84-D8C569B4BFB2", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In nltk version 3.9.4, the `nltk.downloader.Downloader._download_package()` function writes downloaded package bytes to disk and may extract them before enforcing SHA-256 or MD5 checksum validation. This allows an attacker to tamper with the package response body for `info.url` through a compromised mirror, malicious proxy, or other source-substitution condition, leading to the installation of attacker-controlled package bytes. The vulnerability can result in malicious corpus or model content being trusted by downstream users or applications."}, {"lang": "es", "value": "En la versi\u00f3n 3.9.4 de nltk, la funci\u00f3n \u201cnltk.downloader.Downloader._download_package()\u201d escribe los bytes del paquete descargado en el disco y puede extraerlos antes de aplicar la validaci\u00f3n de suma de comprobaci\u00f3n SHA-256 o MD5. Esto permite a un atacante manipular el cuerpo de la respuesta del paquete para \u201cinfo.url\u201d a trav\u00e9s de un espejo comprometido, un proxy malicioso u otra condici\u00f3n de sustituci\u00f3n de origen, lo que lleva a la instalaci\u00f3n de bytes de paquete controlados por el atacante. La vulnerabilidad puede resultar en que contenido malicioso de corpus o modelo sea confiado por usuarios o aplicaciones posteriores."}], "id": "CVE-2026-12259", "lastModified": "2026-10-23T22:10:00.160", "metrics": {"cvssMetricV30": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 5.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N", "version": "3.0"}, "exploitabilityScore": 1.6, "impactScore": 3.6, "source": "security@huntr.dev", "type": "Secondary"}], "cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-12259", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2026-08-03T14:55:19.698104Z", "version": "2.0.3"}}]}, "published": "2026-08-03T08:17:17.880", "references": [{"source": "security@huntr.dev", "tags": ["Permissions Required"], "url": "https://huntr.com/bounties/659ccf6d-12d4-4d4a-84c0-078633c35a5d"}], "sourceIdentifier": "security@huntr.dev", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-494"}], "source": "security@huntr.dev", "type": "Secondary"}]}

{"bugzilla": {"description": "nltk: nltk: Installation of attacker-controlled packages due to improper checksum validation", "id": "2510340", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2510340"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.3", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N", "status": "draft"}, "cwe": "CWE-354", "details": ["A flaw was found in nltk. The `nltk.downloader.Downloader._download_package()` function does not enforce SHA-256 or MD5 checksum validation before writing and extracting downloaded package bytes to disk. A remote attacker can exploit this by tampering with the package response body through a compromised mirror, malicious proxy, or other source-substitution condition. This can lead to the installation of attacker-controlled package bytes, resulting in malicious content being trusted by downstream users or applications."], "name": "CVE-2026-12259", "package_state": [{"cpe": "cpe:/a:redhat:exploit_intelligence:0", "fix_state": "Out of support scope", "package_name": "exploit-intelligence-tech-preview/vulnerability-analysis-rhel9", "product_name": "Exploit Intelligence"}, {"cpe": "cpe:/a:redhat:lightspeed_core", "fix_state": "Fix deferred", "package_name": "lightspeed-core/lightspeed-stack-rhel9", "product_name": "Lightspeed Core"}, {"cpe": "cpe:/a:redhat:lightspeed_core", "fix_state": "Fix deferred", "package_name": "lightspeed-core/rag-tool-cpu-rhel9", "product_name": "Lightspeed Core"}, {"cpe": "cpe:/a:redhat:lightspeed_core", "fix_state": "Fix deferred", "package_name": "lightspeed-core/rag-tool-cuda-12.9-rhel9", "product_name": "Lightspeed Core"}, {"cpe": "cpe:/a:redhat:openshift_lightspeed", "fix_state": "Fix deferred", "package_name": "openshift-lightspeed/lightspeed-ocp-rag-rhel9", "product_name": "OpenShift Lightspeed"}, {"cpe": "cpe:/a:redhat:openshift_lightspeed", "fix_state": "Fix deferred", "package_name": "openshift-lightspeed/lightspeed-service-api-rhel9", "product_name": "OpenShift Lightspeed"}, {"cpe": "cpe:/a:redhat:openshift_lightspeed", "fix_state": "Fix deferred", "package_name": "openshift-lightspeed-tech-preview/lightspeed-rag-tool-rhel9", "product_name": "OpenShift Lightspeed"}, {"cpe": "cpe:/a:redhat:ansible_automation_platform:2", "fix_state": "Out of support scope", "package_name": "ansible-automation-platform-25/lightspeed-chatbot-rhel8", "product_name": "Red Hat Ansible Automation Platform 2"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-llama-stack-core-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-ta-lmes-job-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-trustyai-garak-lls-provider-dsp-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-trustyai-nemo-guardrails-server-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}], "public_date": "2026-08-03T07:09:35Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-12259\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-12259\nhttps://huntr.com/bounties/659ccf6d-12d4-4d4a-84c0-078633c35a5d"], "threat_severity": "Moderate"}

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