Affected: Homebrew: acronym

## Vulnerability Description

The NLTK downloader does not validate the `subdir` and `id` attributes when processing remote XML index files. Attackers can control a remote XML index server to provide malicious values containing path traversal sequences (such as `../`), which can lead to:

1. **Arbitrary Directory Creation**: Create directories at arbitrary locations in the file system 2. **Arbitrary File Creation**: Create arbitrary files 3. **Arbitrary File Overwrite**: Overwrite critical system files (such as `/etc/passwd`, `~/.ssh/authorized_keys`, etc.)

## Vulnerability Principle

### Key Code Locations

**1. XML Parsing Without Validation** (`nltk/downloader.py:253`) ```python self.filename = os.path.join(subdir, id + ext) ``` - `subdir` and `id` are directly from XML attributes without any validation

**2. Path Construction Without Checks** (`nltk/downloader.py:679`) ```python filepath = os.path.join(download_dir, info.filename) ``` - Directly uses `filename` which may contain path traversal

**3. Unrestricted Directory Creation** (`nltk/downloader.py:687`) ```python os.makedirs(os.path.join(download_dir, info.subdir), exist_ok=True) ``` - Can create arbitrary directories outside the download directory

**4. File Writing Without Protection** (`nltk/downloader.py:695`) ```python with open(filepath, "wb") as outfile: ``` - Can write to arbitrary locations in the file system

### Attack Chain

``` 1. Attacker controls remote XML index server ↓ 2. Provides malicious XM…

NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, the NLTK downloader does not validate the `subdir` and `id` attributes when processing remote XML index files. Attackers can control a remote XML index server to provide malicious values containing path traversal sequences (such as `../`), which can lead to arbitrary directory creation, arbitrary file creation, and arbitrary file overwrite. Commit 89fe2ec2c6bae6e2e7a46dad65cc34231976ed8a patches the issue.

Affected: PyPI: nltk

## Vulnerability Description

The NLTK downloader does not validate the `subdir` and `id` attributes when processing remote XML index files. Attackers can control a remote XML index server to provide malicious values containing path traversal sequences (such as `../`), which can lead to:

1. **Arbitrary Directory Creation**: Create directories at arbitrary locations in the file system 2. **Arbitrary File Creation**: Create arbitrary files 3. **Arbitrary File Overwrite**: Overwrite critical system files (such as `/etc/passwd`, `~/.ssh/authorized_keys`, etc.)

## Vulnerability Principle

### Key Code Locations

**1. XML Parsing Without Validation** (`nltk/downloader.py:253`) ```python self.filename = os.path.join(subdir, id + ext) ``` - `subdir` and `id` are directly from XML attributes without any validation

**2. Path Construction Without Checks** (`nltk/downloader.py:679`) ```python filepath = os.path.join(download_dir, info.filename) ``` - Directly uses `filename` which may contain path traversal

**3. Unrestricted Directory Creation** (`nltk/downloader.py:687`) ```python os.makedirs(os.path.join(download_dir, info.subdir), exist_ok=True) ``` - Can create arbitrary directories outside the download directory

**4. File Writing Without Protection** (`nltk/downloader.py:695`) ```python with open(filepath, "wb") as outfile: ``` - Can write to arbitrary locations in the file system

### Attack Chain

``` 1. Attacker controls remote XML index server ↓ 2. Provides malicious XM…

Affected: PyPI: nltk

NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, the NLTK downloader does not validate the `subdir` and `id` attributes when processing remote XML index files. Attackers can control a remote XML index server to provide malicious values containing path traversal sequences (such as `../`), which can lead to arbitrary directory creation, arbitrary file creation, and arbitrary file overwrite. Commit 89fe2ec2c6bae6e2e7a46dad65cc34231976ed8a patches the issue.

vllm: Server Side request forgery (SSRF) in MediaConnector feast: Feast: Remote Code Execution via insecure YAML deserialization openshift-ai: Trusty AI Grants All Authenticated users to list pods in any namespace nltk: Zip Slip Vulnerability in nltk Leading to Code Execution golang: net/url: Memory exhaustion in query parameter parsing in net/url golang: archive/zip: Excessive CPU consumption when building archive index in archive/zip crypto/x509: golang: Denial of Service due to excessive resource consumption via crafted certificate urllib3: urllib3: Unbounded decompression chain leads to resource exhaustion urllib3: urllib3 Streaming API improperly handles highly compressed data cbor2: cbor2: Information Disclosure via shared memory in CBORDecoder reuse aiohttp: AIOHTTP's HTTP Parser auto_decompress feature is vulnerable to zip bomb aiohttp: aiohttp: Denial of Service via specially crafted POST request aiohttp: aiohttp: Denial of Service via memory exhaustion from crafted POST request python-markdown: denial of service via malformed HTML-like sequences nltk: NLTK: Arbitrary file read via improper path validation in `filestring()` function nltk: NLTK: Arbitrary file read via path traversal vulnerability io.vertx/vertx-core: static handler component cache can be manipulated to deny the access to static files google-cloud-aiplatform: google-cloud-aiplatform: Arbitrary code execution via Stored Cross-Site Scripting (XSS) tensorflow: TensorFlow: Local privilege escalation via…

Affected: Ubuntu:Pro:14.04:LTS: nltk, Ubuntu:Pro:16.04:LTS: nltk, Ubuntu:Pro:18.04:LTS: nltk, Ubuntu:Pro:20.04:LTS: nltk, Ubuntu:Pro:22.04:LTS: nltk, Ubuntu:Pro:24.04:LTS: nltk, Ubuntu:25.10: nltk, Ubuntu:Pro:26.04:LTS: nltk

NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, the NLTK downloader does not validate the `subdir` and `id` attributes when processing remote XML index files. Attackers can control a remote XML index server to provide malicious values containing path traversal sequences (such as `../`), which can lead to arbitrary directory creation, arbitrary file creation, and arbitrary file overwrite. Commit 89fe2ec2c6bae6e2e7a46dad65cc34231976ed8a patches the issue.

Ein Angreifer kann mehrere Schwachstellen in IBM App Connect Enterprise ausnutzen, um Dateien zu manipulieren, um einen Denial of Service Angriff durchzuführen, um beliebigen Programmcode auszuführen, und um einen Cross-Site Scripting Angriff durchzuführen.