Arbitrary file read via unchecked fileid
Published Aug 22, 2026 · Updated Aug 22, 2026
Path traversal in NLTK before 3.10.0 allows remote attackers to read arbitrary local files through a controlled fileid. StreamBackedCorpusView._open() sends string paths to builtins.open() without pathsec.validate_path(), bypassing pathsec.ENFORCE. Exploitation requires an application or pipeline to pass attacker-controlled fileid values into an affected corpus view; successful reads expose files accessible to that process.
Summary
What happened
Path traversal in NLTK before 3.10.0 allows remote attackers to read arbitrary local files through a controlled fileid. StreamBackedCorpusView._open() sends string paths to builtins.open() without pathsec.validate_path(), bypassing pathsec.ENFORCE. Exploitation requires an application or pipeline to pass attacker-controlled fileid values into an affected corpus view; successful reads expose files accessible to that process.
The record
- CVE
- CVE-2026-63312
- Published
- Aug 22, 2026
- Updated
- Aug 22, 2026
- Vendor
- NLTK Project
- Product
- NLTK
- Classifications
- CWE-22, T1005
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 22, 2026CVE publishedPublication date reported by the CVE source.
- Aug 22, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <3.10.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
- StreamBackedCorpusView pathsec.ENFORCE bypass PoCproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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