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The CVE-2025-XXXX vulnerability in llama-index versions prior to 0.12.34 stems from an insecure default configuration for the NLTK data directory. Specifically, the library sets this directory to a subdirectory within the codebase itself, which is often world-writable, especially in shared or multi-user environments like development containers or shared hosting. This insecure placement occurs during the library’s initialization process. Instead of utilizing a user-specific, isolated cache location, it defaults to a globally accessible path. This design flaw allows any local user on the same system to list, overwrite, delete, or corrupt the NLTK data files used by the application. Such unauthorized access can lead to a denial of service by deleting critical data files, data tampering by replacing model files with malicious ones, or potentially privilege escalation if the application processes the tampered data with higher privileges.
Platform: llama-index
Version: <0.12.34
Vulnerability : Insecure Temporary File
Severity: High
date: 2025-10-13
Prediction: Patch by 2025-10-20
What Undercode Say:
find /path/to/llama-index -name "nltk_data" -type d -ls ls -la /tmp/global_nltk_cache/ python -c "import nltk; print(nltk.data.path)"
Code snippet showing vulnerable default path from llama_index import ServiceContext The NLTK data path might be set to a non-user-specific location service_context = ServiceContext.from_defaults()
How Exploit:
Local user modifies or deletes files in the world-writable NLTK data directory, causing application failure or executing arbitrary code via poisoned model files.
Protection from this CVE
Upgrade llama-index to version 0.12.34 or later. Manually configure the `NLTK_DATA` environment variable to point to a secure, user-specific directory.
Impact:
Denial of Service, Data Tampering, Privilege Escalation.
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Sources:
Reported By: github.com
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