Vulnerabilidades do Pip Nltk

CVE-2026-79657 Crítica · 9.8 CWE-502 25/08/2026

NLTK anterior à 3.10.3: execução remota de código por desserialização insegura de pickle

As versões do NLTK anteriores à 3.10.3 contêm uma vulnerabilidade de execução remota de código em carregadores de pickle incluídos em lista de permissão, que confiam em namespaces de módulos inteiros em vez de callables seguros específicos. Atacantes podem elaborar payloads de pickle maliciosos que invocam funções perigosas dentro desses namespaces, como ReppTokenizer._execute e numpy.f2py.crackfortran.myeval, por meio de REDUCE do pickle, para executar comandos arbitrários durante o carregamento de artefatos de modelo ou tokenizador.

CVE-2026-78682 Alta · 7.5 CWE-918 24/08/2026

NLTK before 3.10.3 SSRF Protection Bypass via Proxy

NLTK before 3.10.3 contains a server-side request forgery vulnerability in nltk.pathsec.urlopen (and callers nltk.data.load, nltk.downloader.Downloader.index/download) when an HTTP proxy is configured. pathsec.urlopen validates the requested hostname locally, but proxy-handler inheritance disables the safe HTTP/HTTPS handlers so the actual fetch is performed by the proxy against a destination that is never re-validated. An attacker can supply a validated public URL that the proxy forwards to an internal loopback-only service, allowing disclosure of internal HTTP resources, loading of forged downloader indexes, and installation of attacker-chosen package content.

CVE-2026-70626 Média · 6.2 CWE-59 22/08/2026

NLTK before 3.9.4 Symlink Escape via CorpusReader

NLTK versions before 3.9.4 contain a symlink escape vulnerability in CorpusReader.open() that allows local attackers to read arbitrary files outside the corpus root. The vulnerability exists because path validation is lexical and does not account for symlink resolution, enabling attackers to place symlinks inside the corpus root to access files outside the intended boundary.

CVE-2026-66393 Alta · 7.5 CWE-674 22/08/2026

NLTK before 3.9.4 Denial of Service via JSONTaggedDecoder

NLTK versions before 3.9.4 contain an unbounded recursion vulnerability in JSONTaggedDecoder.decode_obj() that allows attackers to cause denial of service by supplying deeply nested JSON structures. Attackers can craft JSON payloads exceeding the recursion limit to trigger an unhandled RecursionError that crashes the Python process.

CVE-2026-65915 Média · 6.5 CWE-284 22/08/2026

NLTK before 3.10.0 Arbitrary File Read via FileSystemPathPointer

NLTK versions before 3.10.0 contain a logic bug in FileSystemPathPointer.open() where the sandbox validation check compares a normalized path against itself, making the security check permanently inert. Attackers can pass file:// URLs to nltk.data.load() to read arbitrary files accessible to the process user, including credentials and configuration files.

CVE-2026-63312 Alta · 7.5 CWE-22 22/08/2026

NLTK StreamBackedCorpusView Bypasses pathsec.ENFORCE Arbitrary File Read

NLTK before 3.10.0 contains an arbitrary local file read vulnerability in StreamBackedCorpusView that bypasses pathsec.ENFORCE by calling builtins.open() directly instead of pathsec.open(). Attackers who control the fileid argument can read arbitrary local files regardless of the ENFORCE setting, including sensitive system files and application credentials.

CVE-2026-63311 Média · 5.3 CWE-918 22/08/2026

NLTK before 3.10.0 SSRF via DNS Resolution Failure

NLTK before 3.10.0 (affected versions <= 3.9.4) contains a server-side request forgery (SSRF) vulnerability in the validate_network_url() function in nltk/pathsec.py. The _resolve_hostname() helper catches OSError and ValueError during socket.getaddrinfo() and returns an empty list; when DNS resolution fails, the validation loop executes no IP checks and the function fails open, allowing urlopen() to proceed without validation. An attacker who can trigger DNS resolution failures or use DNS rebinding can bypass SSRF protections and reach restricted network resources, including cloud metadata endpoints (e.g., 169.254.169.254).

CVE-2026-62388 Alta · 7.5 CWE-1188 22/08/2026

NLTK before 3.10.0 Insecure Default Configuration in pathsec.py

NLTK versions before 3.10.0 default to ENFORCE=False in pathsec.py, causing all security validation functions to emit warnings instead of raising exceptions. Attackers can bypass path traversal and pickle deserialization protections by exploiting the disabled security controls that are only active when manually enabled.

CVE-2026-62385 Alta · 7.5 CWE-73 22/08/2026

NLTK 3.9.4 Path Traversal via FrameNet and NKJP Readers

NLTK versions before 3.10.0 contain a path traversal vulnerability in FramenetCorpusReader and NKJPCorpusReader that allows attackers to parse XML files outside the corpus root by supplying unsafe selectors or poisoned index state. Attackers can exploit frame_by_name, doc, lu, and header methods with crafted parameters to read arbitrary XML files accessible to the application.

CVE-2026-62384 Alta · 7.5 CWE-22 22/08/2026

NLTK FramenetCorpusReader Symlink Sandbox Bypass before 3.10.2

NLTK versions before 3.10.2 contain a symlink-based sandbox bypass in FramenetCorpusReader that allows attackers to read arbitrary XML files outside the corpus root. Attackers can place symlinks with names containing no path separators inside the corpus subdirectory, which pass the path validation guard and are resolved to files outside the intended corpus root when accessed via frame_by_name(), _lu_file(), or doc() methods.

CVE-2026-62383 Média · 5.5 CWE-22 22/08/2026

nltk IPIPANCorpusReader Symlink Arbitrary File Read

nltk versions before 3.10.2 contain a symlink-based arbitrary file read vulnerability in IPIPANCorpusReader methods that bypass nltk.pathsec validation entirely. Attackers can place a symlink in the corpus root directory and read arbitrary files accessible to the process by calling channels(), domains(), categories(), or fileids() methods with the symlink filename.

CVE-2026-71514 Baixa · 3.3 CWE-22 22/08/2026

NLTK 3.9.4 through 3.10.2 Path Traversal via CrubadanCorpusReader pathsec Bypass

NLTK 3.9.4 through 3.10.2 contains a path traversal vulnerability in CrubadanCorpusReader. _load_lang_ngrams joins the corpus root with crubadan_code, the column-0 value read from the corpus table.txt mapping file, and opens the result with the builtin open() rather than the pathsec-validated opener, so os.path.join discards the root when that value is absolute and the read escapes the corpus directory without the containment check nltk.pathsec applies when ENFORCE is set. An attacker who controls a corpus package can disclose file contents outside the corpus root through lang_freq, limited to paths ending in -3grams.txt whose contents parse as token count lines.

CVE-2026-71513 Alta · 8.8 CWE-502 22/08/2026

NLTK 3.10.0 through 3.10.2 Remote Code Execution via AllowlistUnpickler Dotted-Name Bypass

NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only the pickle module string and not the global name, allowing attackers to resolve dotted names by attribute traversal to callables outside the allowlisted namespace. Attackers can craft untrusted transition-parser models that execute arbitrary commands when TransitionParser.parse loads the model through allowlisted_pickle_load.