Arbitrary file read via unchecked corpus paths
Published Mar 4, 2026 · Updated Mar 4, 2026
Path traversal in NLTK 3.9.2 and earlier allows remote attackers to read arbitrary files through crafted CorpusReader file identifiers. CorpusReader.open() passes unchecked absolute paths and parent-directory segments into the corpus root's join-and-open flow, allowing affected reader subclasses to escape the intended root. Exposure requires an application to pass attacker-controlled file identifiers into an affected reader; access is limited to files readable by the Python process.
Summary
What happened
Path traversal in NLTK 3.9.2 and earlier allows remote attackers to read arbitrary files through crafted CorpusReader file identifiers. CorpusReader.open() passes unchecked absolute paths and parent-directory segments into the corpus root's join-and-open flow, allowing affected reader subclasses to escape the intended root. Exposure requires an application to pass attacker-controlled file identifiers into an affected reader; access is limited to files readable by the Python process.
The record
- CVE
- CVE-2026-0847
- Published
- Mar 4, 2026
- Updated
- Mar 4, 2026
- Vendor
- NLTK Project
- Product
- NLTK
- Classifications
- CWE-22, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 4, 2026CVE publishedPublication date reported by the CVE source.
- Mar 4, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=unspecified <=latest
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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