CVE-2021-43854

{"containers": {"cna": {"affected": [{"product": "nltk", "vendor": "nltk", "versions": [{"status": "affected", "version": "< 3.6.5"}]}], "descriptions": [{"lang": "en", "value": "NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. Versions prior to 3.6.5 are vulnerable to regular expression denial of service (ReDoS) attacks. The vulnerability is present in PunktSentenceTokenizer, sent_tokenize and word_tokenize. Any users of this class, or these two functions, are vulnerable to the ReDoS attack. In short, a specifically crafted long input to any of these vulnerable functions will cause them to take a significant amount of execution time. If your program relies on any of the vulnerable functions for tokenizing unpredictable user input, then we would strongly recommend upgrading to a version of NLTK without the vulnerability. For users unable to upgrade the execution time can be bounded by limiting the maximum length of an input to any of the vulnerable functions. Our recommendation is to implement such a limit."}], "metrics": [{"cvssV3_1": {"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"}}], "problemTypes": [{"descriptions": [{"cweId": "CWE-400", "description": "CWE-400: Uncontrolled Resource Consumption", "lang": "en", "type": "CWE"}]}], "providerMetadata": {"dateUpdated": "2021-12-23T17:55:11.000Z", "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M"}, "references": [{"tags": ["x_refsource_CONFIRM"], "url": "https://github.com/nltk/nltk/security/advisories/GHSA-f8m6-h2c7-8h9x"}, {"tags": ["x_refsource_MISC"], "url": "https://github.com/nltk/nltk/issues/2866"}, {"tags": ["x_refsource_MISC"], "url": "https://github.com/nltk/nltk/pull/2869"}, {"tags": ["x_refsource_MISC"], "url": "https://github.com/nltk/nltk/commit/1405aad979c6b8080dbbc8e0858f89b2e3690341"}], "source": {"advisory": "GHSA-f8m6-h2c7-8h9x", "discovery": "UNKNOWN"}, "title": "Inefficient Regular Expression Complexity in nltk", "x_legacyV4Record": {"CVE_data_meta": {"ASSIGNER": "security-advisories@github.com", "ID": "CVE-2021-43854", "STATE": "PUBLIC", "TITLE": "Inefficient Regular Expression Complexity in nltk"}, "affects": {"vendor": {"vendor_data": [{"product": {"product_data": [{"product_name": "nltk", "version": {"version_data": [{"version_value": "< 3.6.5"}]}}]}, "vendor_name": "nltk"}]}}, "data_format": "MITRE", "data_type": "CVE", "data_version": "4.0", "description": {"description_data": [{"lang": "eng", "value": "NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. Versions prior to 3.6.5 are vulnerable to regular expression denial of service (ReDoS) attacks. The vulnerability is present in PunktSentenceTokenizer, sent_tokenize and word_tokenize. Any users of this class, or these two functions, are vulnerable to the ReDoS attack. In short, a specifically crafted long input to any of these vulnerable functions will cause them to take a significant amount of execution time. If your program relies on any of the vulnerable functions for tokenizing unpredictable user input, then we would strongly recommend upgrading to a version of NLTK without the vulnerability. For users unable to upgrade the execution time can be bounded by limiting the maximum length of an input to any of the vulnerable functions. Our recommendation is to implement such a limit."}]}, "impact": {"cvss": {"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"}}, "problemtype": {"problemtype_data": [{"description": [{"lang": "eng", "value": "CWE-400: Uncontrolled Resource Consumption"}]}]}, "references": {"reference_data": [{"name": "https://github.com/nltk/nltk/security/advisories/GHSA-f8m6-h2c7-8h9x", "refsource": "CONFIRM", "url": "https://github.com/nltk/nltk/security/advisories/GHSA-f8m6-h2c7-8h9x"}, {"name": "https://github.com/nltk/nltk/issues/2866", "refsource": "MISC", "url": "https://github.com/nltk/nltk/issues/2866"}, {"name": "https://github.com/nltk/nltk/pull/2869", "refsource": "MISC", "url": "https://github.com/nltk/nltk/pull/2869"}, {"name": "https://github.com/nltk/nltk/commit/1405aad979c6b8080dbbc8e0858f89b2e3690341", "refsource": "MISC", "url": "https://github.com/nltk/nltk/commit/1405aad979c6b8080dbbc8e0858f89b2e3690341"}]}, "source": {"advisory": "GHSA-f8m6-h2c7-8h9x", "discovery": "UNKNOWN"}}}, "adp": [{"providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T04:10:16.281Z"}, "title": "CVE Program Container", "references": [{"tags": ["x_refsource_CONFIRM", "x_transferred"], "url": "https://github.com/nltk/nltk/security/advisories/GHSA-f8m6-h2c7-8h9x"}, {"tags": ["x_refsource_MISC", "x_transferred"], "url": "https://github.com/nltk/nltk/issues/2866"}, {"tags": ["x_refsource_MISC", "x_transferred"], "url": "https://github.com/nltk/nltk/pull/2869"}, {"tags": ["x_refsource_MISC", "x_transferred"], "url": "https://github.com/nltk/nltk/commit/1405aad979c6b8080dbbc8e0858f89b2e3690341"}]}]}, "cveMetadata": {"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "assignerShortName": "GitHub_M", "cveId": "CVE-2021-43854", "datePublished": "2021-12-23T17:55:11.000Z", "dateReserved": "2021-11-16T00:00:00.000Z", "dateUpdated": "2024-08-04T04:10:16.281Z", "state": "PUBLISHED"}, "dataType": "CVE_RECORD", "dataVersion": "5.1"}

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{"affected": [{"affectedData": [{"product": "nltk", "vendor": "nltk", "versions": [{"status": "affected", "version": "< 3.6.5"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*", "matchCriteriaId": "355BC362-D4FF-4893-9F37-B97D23E48267", "versionEndExcluding": "3.6.5", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. Versions prior to 3.6.5 are vulnerable to regular expression denial of service (ReDoS) attacks. The vulnerability is present in PunktSentenceTokenizer, sent_tokenize and word_tokenize. Any users of this class, or these two functions, are vulnerable to the ReDoS attack. In short, a specifically crafted long input to any of these vulnerable functions will cause them to take a significant amount of execution time. If your program relies on any of the vulnerable functions for tokenizing unpredictable user input, then we would strongly recommend upgrading to a version of NLTK without the vulnerability. For users unable to upgrade the execution time can be bounded by limiting the maximum length of an input to any of the vulnerable functions. Our recommendation is to implement such a limit."}, {"lang": "es", "value": "NLTK (Natural Language Toolkit) es un conjunto de m\u00f3dulos de c\u00f3digo abierto de Python, conjuntos de datos y tutoriales que apoyan la investigaci\u00f3n y el desarrollo en el procesamiento del lenguaje natural. Las Versiones anteriores a 3.6.5, son vulnerables a ataques de denegaci\u00f3n de servicio con expresiones regulares (ReDoS). La vulnerabilidad est\u00e1 presente en PunktSentenceTokenizer, sent_tokenize y word_tokenize. Cualquier usuario de esta clase, o de estas dos funciones, es vulnerable al ataque ReDoS. En resumen, una entrada larga espec\u00edficamente dise\u00f1ada para cualquiera de estas funciones vulnerables causar\u00e1 que tomen una cantidad significativa de tiempo de ejecuci\u00f3n. Si su programa depende de cualquiera de las funciones vulnerables para tokenizar entradas de usuario imprevisibles, le recomendamos encarecidamente que actualice a una versi\u00f3n de NLTK sin la vulnerabilidad. Para usuarios que no puedan actualizarse, el tiempo de ejecuci\u00f3n puede limitarse mediante la limitaci\u00f3n de la longitud m\u00e1xima de una entrada a cualquiera de las funciones vulnerables. Nuestra recomendaci\u00f3n es implementar dicho l\u00edmite"}], "id": "CVE-2021-43854", "lastModified": "2026-06-17T04:11:34.653", "metrics": {"cvssMetricV2": [{"acInsufInfo": false, "baseSeverity": "MEDIUM", "cvssData": {"accessComplexity": "LOW", "accessVector": "NETWORK", "authentication": "NONE", "availabilityImpact": "PARTIAL", "baseScore": 5.0, "confidentialityImpact": "NONE", "integrityImpact": "NONE", "vectorString": "AV:N/AC:L/Au:N/C:N/I:N/A:P", "version": "2.0"}, "exploitabilityScore": 10.0, "impactScore": 2.9, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "source": "nvd@nist.gov", "type": "Primary", "userInteractionRequired": false}], "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": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2021-12-23T18:15:07.327", "references": [{"source": "security-advisories@github.com", "tags": ["Patch", "Third Party Advisory"], "url": "https://github.com/nltk/nltk/commit/1405aad979c6b8080dbbc8e0858f89b2e3690341"}, {"source": "security-advisories@github.com", "tags": ["Exploit", "Issue Tracking", "Patch", "Third Party Advisory"], "url": "https://github.com/nltk/nltk/issues/2866"}, {"source": "security-advisories@github.com", "tags": ["Exploit", "Patch", "Third Party Advisory"], "url": "https://github.com/nltk/nltk/pull/2869"}, {"source": "security-advisories@github.com", "tags": ["Exploit", "Patch", "Third Party Advisory"], "url": "https://github.com/nltk/nltk/security/advisories/GHSA-f8m6-h2c7-8h9x"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch", "Third Party Advisory"], "url": "https://github.com/nltk/nltk/commit/1405aad979c6b8080dbbc8e0858f89b2e3690341"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Issue Tracking", "Patch", "Third Party Advisory"], "url": "https://github.com/nltk/nltk/issues/2866"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Patch", "Third Party Advisory"], "url": "https://github.com/nltk/nltk/pull/2869"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Exploit", "Patch", "Third Party Advisory"], "url": "https://github.com/nltk/nltk/security/advisories/GHSA-f8m6-h2c7-8h9x"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Modified", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-400"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

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