{"id":"GHSA-gx65-c5hj-vpv5","summary":"Duplicate Advisory: [CWE-502] Unsafe Pickle Deserialization in TransitionParser Allows Remote Code Execution","details":"## Duplicate Advisory\n\nThis advisory has been withdrawn because it is a duplicate of GHSA-rhp5-r9x4-f5g2. This link is maintained to preserve external references.\n\n## Original Description\nNLTK before 3.10.0 (affected versions \u003c=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 Fixed in 3.10.0.","modified":"2026-09-02T15:00:09.005033152Z","published":"2026-08-25T03:32:11Z","withdrawn":"2026-09-02T14:40:50Z","database_specific":{"nvd_published_at":"2026-08-25T02:16:53Z","cwe_ids":["CWE-502"],"severity":"CRITICAL","github_reviewed":true,"github_reviewed_at":"2026-09-02T14:40:50Z"},"references":[{"type":"WEB","url":"https://github.com/nltk/nltk/security/advisories/GHSA-rhp5-r9x4-f5g2"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-78683"},{"type":"WEB","url":"https://www.vulncheck.com/advisories/nltk-before-remote-code-execution-via-unsafe-pickle-deserialization"}],"affected":[{"package":{"name":"nltk","ecosystem":"PyPI","purl":"pkg:pypi/nltk"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"3.9.4"}]}],"versions":["0.8","0.9","0.9.3","0.9.4","0.9.5","0.9.6","0.9.7","0.9.8","0.9.9","2.0.1","2.0.1rc1","2.0.1rc2-git","2.0.1rc3","2.0.1rc4","2.0.2","2.0.3","2.0.4","2.0.5","2.0b4","2.0b5","2.0b6","2.0b7","2.0b8","2.0b9","3.0.0","3.0.0b1","3.0.0b2","3.0.1","3.0.2","3.0.3","3.0.4","3.0.5","3.1","3.2","3.2.1","3.2.2","3.2.3","3.2.4","3.2.5","3.3","3.4","3.4.1","3.4.2","3.4.3","3.4.4","3.4.5","3.5","3.5b1","3.6","3.6.1","3.6.2","3.6.3","3.6.4","3.6.5","3.6.6","3.6.7","3.7","3.8","3.8.1","3.9","3.9.1","3.9.2","3.9.3","3.9.4","3.9b1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/08/GHSA-gx65-c5hj-vpv5/GHSA-gx65-c5hj-vpv5.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H"},{"type":"CVSS_V4","score":"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/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"}]}