CVE-2026-70626

NLTK versions before 3.9.4 contain a symlink escape vulnerability in CorpusReader.open() that allows local attackers to read arbitrary files outside the corpus root. The vulnerability exists because path validation is lexical and does not account for symlink resolution, enabling attackers to place symlinks inside the corpus root to access files outside the intended boundary.

CVSS v3 6.2 MEDIUM

6.2^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.5 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/nltk/nltk/security/advisories/GHSA-r6gq-whwq-mvg9	Exploit Vendor Advisory
https://www.vulncheck.com/advisories/nltk-before-symlink-escape-via-corpusreader	Vendor Advisory
https://github.com/nltk/nltk/security/advisories/GHSA-r6gq-whwq-mvg9	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*

History

14 Oct 2026, 13:10

Type	Values Removed	Values Added
Summary		(es) Las versiones de NLTK anteriores a la 3.9.4 contienen una vulnerabilidad de escape de enlace simbólico en CorpusReader.open() que permite a atacantes locales leer archivos arbitrarios fuera de la raíz del corpus. La vulnerabilidad existe porque la validación de rutas es léxica y no tiene en cuenta la resolución de enlaces simbólicos, lo que permite a los atacantes colocar enlaces simbólicos dentro de la raíz del corpus para acceder a archivos fuera del límite previsto.

Information

Published : 2026-08-22 15:16

Updated : 2026-10-14 13:10

NVD link : CVE-2026-70626

Mitre link : CVE-2026-70626

CVE.ORG link : CVE-2026-70626

JSON object : View

Products Affected

nltk

nltk

CWE

CWE-59

Improper Link Resolution Before File Access ('Link Following')

{"id": "CVE-2026-70626", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-70626", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-08-24T19:49:24.557944Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 6.2, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 3.6, "exploitabilityScore": 2.5}], "cvssMetricV40": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "cvssData": {"Safety": "NOT_DEFINED", "version": "4.0", "Recovery": "NOT_DEFINED", "baseScore": 8.6, "Automatable": "NOT_DEFINED", "attackVector": "LOCAL", "baseSeverity": "HIGH", "valueDensity": "NOT_DEFINED", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/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": "HIGH", "integrityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "subAvailabilityImpact": "NONE", "vulnAvailabilityImpact": "HIGH", "availabilityRequirement": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "subConfidentialityImpact": "NONE", "vulnConfidentialityImpact": "HIGH", "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": "disclosure@vulncheck.com", "affectedData": [{"vendor": "nltk", "product": "nltk", "versions": [{"status": "affected", "version": "0", "lessThan": "3.9.4", "versionType": "semver"}, {"status": "unaffected", "version": "3.9.4", "versionType": "semver"}], "packageURL": "pkg:pypi/nltk", "defaultStatus": "unaffected"}]}], "published": "2026-08-22T15:16:21.100", "references": [{"url": "https://github.com/nltk/nltk/security/advisories/GHSA-r6gq-whwq-mvg9", "tags": ["Exploit", "Vendor Advisory"], "source": "disclosure@vulncheck.com"}, {"url": "https://www.vulncheck.com/advisories/nltk-before-symlink-escape-via-corpusreader", "tags": ["Vendor Advisory"], "source": "disclosure@vulncheck.com"}, {"url": "https://github.com/nltk/nltk/security/advisories/GHSA-r6gq-whwq-mvg9", "tags": ["Exploit", "Vendor Advisory"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "disclosure@vulncheck.com", "description": [{"lang": "en", "value": "CWE-59"}]}], "descriptions": [{"lang": "en", "value": "NLTK versions before 3.9.4 contain a symlink escape vulnerability in CorpusReader.open() that allows local attackers to read arbitrary files outside the corpus root. The vulnerability exists because path validation is lexical and does not account for symlink resolution, enabling attackers to place symlinks inside the corpus root to access files outside the intended boundary."}, {"lang": "es", "value": "Las versiones de NLTK anteriores a la 3.9.4 contienen una vulnerabilidad de escape de enlace simb\u00f3lico en CorpusReader.open() que permite a atacantes locales leer archivos arbitrarios fuera de la ra\u00edz del corpus. La vulnerabilidad existe porque la validaci\u00f3n de rutas es l\u00e9xica y no tiene en cuenta la resoluci\u00f3n de enlaces simb\u00f3licos, lo que permite a los atacantes colocar enlaces simb\u00f3licos dentro de la ra\u00edz del corpus para acceder a archivos fuera del l\u00edmite previsto."}], "lastModified": "2026-10-14T13:10:00.187", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "A5471378-2B80-492B-B6BC-E6E9AE4F5179", "versionEndExcluding": "3.9.4"}], "operator": "OR"}]}], "sourceIdentifier": "disclosure@vulncheck.com"}