Path Traversal in nltk/nltk

Answer in brief

CVE-2026-0847 records a High severity (CVSS 7.5) vulnerability in Path Traversal in nltk/nltk. The current sources do not mark it as known exploited. The current feed maps nltk/nltk/nltk (generic), nltk (pip). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Mar 4, 2026Updated Sep 16, 2026Source checked Sep 16, 2026First seen by HOL Jun 11, 2026Material review Sep 16, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Not reported

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps nltk/nltk/nltk (generic), nltk (pip). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
nltk/nltk/nltkgeneric	unspecified	Not reported
nltkpip	<=3.9.2	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for nltk/nltk/nltk, nltk.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Mar 4, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 16, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jun 11, 2026

Sources and claim methodology

Upstream source description

A vulnerability in NLTK versions up to and including 3.9.2 allows arbitrary file read via path traversal in multiple CorpusReader classes, including WordListCorpusReader, TaggedCorpusReader, and BracketParseCorpusReader. These classes fail to properly sanitize or validate file paths, enabling attackers to traverse directories and access sensitive files on the server. This issue is particularly critical in scenarios where user-controlled file inputs are processed, such as in machine learning APIs, chatbots, or NLP pipelines. Exploitation of this vulnerability can lead to unauthorized access to sensitive files, including system files, SSH private keys, and API tokens, and may potentially escalate to remote code execution when combined with other vulnerabilities.

Quoted source text, attributed separately from HOL analysis.