Bug 2449824 (CVE-2026-33236)

Summary: CVE-2026-33236 nltk: NLTK: Arbitrary file overwrite and creation via path traversal in XML index files
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: anpicker, bparees, dschmidt, ebourniv, erezende, hasun, jfula, jkoehler, jlanda, jowilson, jwong, kshier, lgallett, lphiri, nyancey, omaciel, ometelka, ptisnovs, sbunciak, simaishi, smcdonal, stcannon, syedriko, teagle, ttakamiy, xdharmai, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in NLTK (Natural Language Toolkit), a suite of open-source Python modules for Natural Language Processing. The NLTK downloader does not validate `subdir` and `id` attributes when processing remote XML index files. A remote attacker can exploit this path traversal vulnerability by controlling a malicious XML index server, providing specially crafted values. This can lead to arbitrary directory creation, arbitrary file creation, and arbitrary file overwrite on the system where NLTK is used.
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Description OSIDB Bzimport 2026-03-20 23:02:14 UTC
NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, the NLTK downloader does not validate the `subdir` and `id` attributes when processing remote XML index files. Attackers can control a remote XML index server to provide malicious values containing path traversal sequences (such as `../`), which can lead to arbitrary directory creation, arbitrary file creation, and arbitrary file overwrite. Commit 89fe2ec2c6bae6e2e7a46dad65cc34231976ed8a patches the issue.