CVE-2026-63310

NLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation...

CVE-2026-62384

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 validatio...

CVE-2026-62388

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 activ...

CVE-2026-62385

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 framebyname, doc, lu, and header methods wi...

CVE-2026-62383

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,...

CVE-2026-71513

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...

CVE-2026-71514

NLTK 3.9.4 through 3.10.2 contains a path traversal vulnerability in CrubadanCorpusReader. loadlangngrams joins the corpus root with crubadancode, 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, s...

CVE-2026-70626

NLTK versions before 3.9.4 are affected by a symlink escape vulnerability in CorpusReader.open() . The root cause is that path validation is purely lexical and does not resolve symlinks, allowing a local attacker to place a symlink inside the corpus root to read arbitrary files outside the intend...

CVE-2026-70626 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...

EUVD-2026-64314

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...

CVE-2026-70626

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...

CVE-2026-70626 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...

CVE-2026-66393 NLTK before 3.9.4 Denial of Service via JSONTaggedDecoder

NLTK versions before 3.9.4 contain an unbounded recursion vulnerability in JSONTaggedDecoder.decodeobj 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 RecursionErro...

CVE-2026-66393 NLTK before 3.9.4 Denial of Service via JSONTaggedDecoder

NLTK versions before 3.9.4 contain an unbounded recursion vulnerability in JSONTaggedDecoder.decodeobj 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 RecursionErro...

EUVD-2026-64310

NLTK versions before 3.9.4 contain an unbounded recursion vulnerability in JSONTaggedDecoder.decodeobj 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 RecursionErro...

CVE-2026-66393

NLTK versions before 3.9.4 contain an unbounded recursion vulnerability in JSONTaggedDecoder.decodeobj 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 RecursionErro...

CVE-2026-66393

NLTK versions before 3.9.4 are affected by an unbounded recursion vulnerability in JSONTaggedDecoder.decode_obj() . An attacker can supply a deeply nested JSON structure that exceeds Python's recursion limit, triggering an unhandled RecursionError that crashes the process, resulting in denial of ...

CVE-2026-65915 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...

CVE-2026-65915

NLTK versions before 3.10.0 contain a logic bug in FileSystemPathPointer.open() where the sandbox validation check compares a normalized path against itself, rendering the security check permanently inert. An attacker with low privileges can pass file:// URLs to nltk.data.load() to read arbitrary...

CVE-2026-65915 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...