Nltk Nltk vulnerabilities

CVE-2026-0848 [CRITICAL] CWE-20 CVE-2026-0848: NLTK versions <=3.9.2 are vulnerable to arbitrary code execution due to improper input validation in NLTK versions <=3.9.2 are vulnerable to arbitrary code execution due to improper input validation in the StanfordSegmenter module. The module dynamically loads external Java .jar files without verification or sandboxing. An attacker can supply or replace the JAR file, enabling the execution of arbitrary Java bytecode at import time. This vulnerabilit

CVE-2025-14009 [HIGH] CWE-94 CVE-2025-14009: A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all version A critical vulnerability exists in the NLTK downloader component of nltk/nltk, affecting all versions. The _unzip_iter function in nltk/downloader.py uses zipfile.extractall() without performing path validation or security checks. This allows attackers to craft malicious zip packages that, when downloaded and extracted by NLTK, can execute arbitrary co

CVE-2026-0847 [HIGH] CWE-22 CVE-2026-0847: A vulnerability in NLTK versions up to and including 3.9.2 allows arbitrary file read via path trave 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 o

CVE-2026-0846 [HIGH] CWE-36 CVE-2026-0846: A vulnerability in the `filestring()` function of the `nltk.util` module in nltk version 3.9.2 allow A vulnerability in the `filestring()` function of the `nltk.util` module in nltk version 3.9.2 allows arbitrary file read due to improper validation of input paths. The function directly opens files specified by user input without sanitization, enabling attackers to access sensitive system files by providing absolute paths or traversal paths. This vulner

CVE-2026-12243 [HIGH] CWE-22 CVE-2026-12243: NLTK version 3.9.4 is vulnerable to a path traversal attack due to an incomplete fix for GitHub Issu NLTK version 3.9.4 is vulnerable to a path traversal attack due to an incomplete fix for GitHub Issue #3504. The `_UNSAFE_NO_PROTOCOL_RE` regex in `nltk/data.py` checks for literal `../` sequences but fails to account for percent-encoded traversal sequences such as `..%2f`. The `url2pathname()` function decodes these sequences after the validation step

CVE-2021-3828 [HIGH] CWE-1333 CVE-2021-3828: nltk is vulnerable to Inefficient Regular Expression Complexity nltk is vulnerable to Inefficient Regular Expression Complexity

CVE-2021-3842 [HIGH] CWE-1333 CVE-2021-3842: nltk is vulnerable to Inefficient Regular Expression Complexity nltk is vulnerable to Inefficient Regular Expression Complexity

CVE-2026-12261 [MEDIUM] CWE-284 CVE-2026-12261: A vulnerability in `nltk.downloader` in nltk/nltk versions <= 3.9.4 allows for cross-package resourc A vulnerability in `nltk.downloader` in nltk/nltk versions <= 3.9.4 allows for cross-package resource and model poisoning. The downloader extracts package archives into shared namespaces such as `corpora/` and `taggers/` instead of package-isolated roots, and validates package integrity only after the archive has been written and extracted. This des

CVE-2026-12259 [MEDIUM] CWE-494 CVE-2026-12259: In nltk version 3.9.4, the `nltk.downloader.Downloader._download_package()` function writes download In nltk version 3.9.4, the `nltk.downloader.Downloader._download_package()` function writes downloaded package bytes to disk and may extract them before enforcing SHA-256 or MD5 checksum validation. This allows an attacker to tamper with the package response body for `info.url` through a compromised mirror, malicious proxy, or other source-substitut

CVE-2026-12372 [LOW] CWE-918 CVE-2026-12372: A Server-Side Request Forgery (SSRF) vulnerability exists in nltk/nltk versions 3.9.4 and the curren A Server-Side Request Forgery (SSRF) vulnerability exists in nltk/nltk versions 3.9.4 and the current develop branch. The `nltk.pathsec.validate_network_url()` function, intended to prevent SSRF by rejecting internal network addresses, fails to reject IPs in the RFC 6598 shared address space (`100.64.0.0/10`). This occurs because Python's `ipaddress` m

CVE-2026-12199 [HIGH] CWE-306 Unauthenticated Denial of Service in nltk.app.wordnet_app Unauthenticated Denial of Service in nltk.app.wordnet_app A vulnerability in `nltk.app.wordnet_app` up to version 3.9.3 allows unauthenticated remote shutdown of the local WordNet Browser HTTP server when started in its default mode. The server listens on all interfaces and processes a specific unauthenticated GET request (`/SHUTDOWN%20THE%20SERVER`) to terminate the process immediately via `os._exit(0)`. Th