CVE-2026-0847

HighPublic PoC

Published: 04 March 2026

Published

04 March 2026

Modified

28 April 2026

KEV Added

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Patch

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CVSS Score 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Score 0.0008 22.7th percentile

Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-0847 is a high-severity Path Traversal (CWE-22) vulnerability in Nltk Nltk. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 22.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

This vulnerability is AI-related — categorised as NLP Libraries.

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 2 other techniques.

Threat & Defense Details

Likely Mitigating ControlsAI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

SI-10 Information Input Validation

addresses: CWE-22

Validates pathnames and filenames to prevent traversal outside intended directories.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1005 Data from Local System Collection

Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.

attack.mitre.org →

T1552.001 Credentials In Files Credential Access

Adversaries may search local file systems and remote file shares for files containing insecurely stored credentials.

attack.mitre.org →

Why these techniques?

Path traversal in public-facing NLTK deployment enables remote exploitation (T1190) and direct unauthorized file reads including credentials (T1005, T1552.001).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD 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.

Deeper analysisAI

CVE-2026-0847 is a path traversal vulnerability (CWE-22) in NLTK versions up to and including 3.9.2. It affects multiple CorpusReader classes, including WordListCorpusReader, TaggedCorpusReader, and BracketParseCorpusReader, which fail to properly sanitize or validate file paths. This enables attackers to traverse directories and access arbitrary files on the server where NLTK is deployed.

Remote unauthenticated attackers can exploit this vulnerability with low complexity, as indicated by its CVSS v3.1 score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N). Exploitation requires scenarios where user-controlled inputs are processed as file paths, such as in machine learning APIs, chatbots, or NLP pipelines. Successful attacks allow unauthorized reads of sensitive files, including system files, SSH private keys, and API tokens, and may escalate to remote code execution when combined with other vulnerabilities.

Mitigation details are available in the Huntr advisory at https://huntr.com/bounties/fc69914f-36a9-4c18-8503-10013b39f966.

This vulnerability is particularly critical for AI/ML and NLP applications relying on NLTK for corpus processing.