EUVD Vulnerability Catalog
EUVD-2026-65229
Severity: CRITICAL
Base Score: 9.4
CVSS Version: 4.0
Vulnerability Description
NLTK before 3.10.0 (affected versions <=3.9.4) contains an unsafe pickle deserialization vulnerability in the TransitionParser.parse() method (nltk/parse/transitionparser.py). The method calls pickle_load() with the default restricted=False, routing deserialization through WarningUnpickler, which does not override find_class() and therefore permits arbitrary class resolution. When an application loads an attacker-crafted model file, embedded pickle gadget chains execute arbitrary Python code with the privileges of the user running the application. NLTK provides a RestrictedUnpickler for safe deserialization, but it is not used by production code paths. Fixed in 3.10.0.
CVSS Vector Analysis
Below is the complete, human-readable breakdown of the CVSS metric string: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
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Attack Vector (AV): Network
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Attack Complexity (AC): Low
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Attack Requirements (AT): None
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Privileges Required (PR): None
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User Interaction (UI): Passive
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Vulnerability Confidentiality Impact (VC): High
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Vulnerability Integrity Impact (VI): High
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Vulnerability Availability Impact (VA): High
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Subsequent Confidentiality Impact (SC): High
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Subsequent Integrity Impact (SI): High
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Subsequent Availability Impact (SA): High
Affected Vendors & Systems
Vendor
nltk
References & Advisory Links
Metadata Profile
Database Authority
European Union Agency for Cybersecurity (ENISA) EUVD
Assigner
VulnCheck
EPSS Probability
0
Known Aliases
CVE-2026-78683
GHSA-gx65-c5hj-vpv5
Published On
2026-08-25
Last Updated
2026-08-25