GHSA-VP2X-QP44-57V7 NLTK: Quadratic CPU Exhaustion in `XMLCorpusView._read_xml_fragment()`

Summary XMLCorpusView.readxmlfragment reads a corpus file in 1 KiB blocks, appending each block to a growing fragment string, then calls VALIDXMLRE.matchfragment on the full accumulated buffer every iteration. Because each iteration rescans the entire accumulated fragment, the total amount of wor...

NLTK: Quadratic CPU Exhaustion in `XMLCorpusView._read_xml_fragment()`

Summary XMLCorpusView.readxmlfragment reads a corpus file in 1 KiB blocks, appending each block to a growing fragment string, then calls VALIDXMLRE.matchfragment on the full accumulated buffer every iteration. Because each iteration rescans the entire accumulated fragment, the total amount of wor...

GHSA-FF5C-CP5C-9WJF NLTK: Uncontrolled resource consumption in RecursiveDescentParser via ambiguous or left-recursive grammars

nltk.parse.RecursiveDescentParser and SteppingRecursiveDescentParser enumerate parses top-down with no bound on the number of recursive steps. A small, crafted context-free grammar makes a short input consume unbounded CPU and/or exhaust the Python recursion stack, pinning a process indefinitely ...

NLTK: Uncontrolled resource consumption in RecursiveDescentParser via ambiguous or left-recursive grammars

nltk.parse.RecursiveDescentParser and SteppingRecursiveDescentParser enumerate parses top-down with no bound on the number of recursive steps. A small, crafted context-free grammar makes a short input consume unbounded CPU and/or exhaust the Python recursion stack, pinning a process indefinitely ...

EUVD-2026-67074

NLTK: Uncontrolled recursion in nltk.featstruct.FeatStructReader causes unhandled RecursionError DoS via deeply nested feature-structure input...

NLTK: Uncontrolled recursion in nltk.featstruct.FeatStructReader causes unhandled RecursionError (DoS) via deeply nested feature-structure input

Summary nltk.featstruct.FeatStructReader used by FeatStructstr and by FeatureGrammar.fromstring parses feature-structure strings such as a=1 with a recursive-descent parser that has no nesting-depth limit. A small, trivially-crafted input 700 bytes with deeply nested brackets drives the parser pa...

GHSA-CW6X-M8JW-QMRH NLTK: Uncontrolled recursion in nltk.featstruct.FeatStructReader causes unhandled RecursionError (DoS) via deeply nested feature-structure input

Summary nltk.featstruct.FeatStructReader used by FeatStructstr and by FeatureGrammar.fromstring parses feature-structure strings such as a=1 with a recursive-descent parser that has no nesting-depth limit. A small, trivially-crafted input 700 bytes with deeply nested brackets drives the parser pa...

GHSA-M4RF-3FR8-XWX3 NLTK: JVM argument injection bypass via per-call options in the NLTK Stanford wrappers (incomplete fix of CVE-2026-12841)

Vulnerability The fix for CVE-2026-12841 CWE-88, JVM argument injection added validatejavaoptions to block dangerous JVM flags such as -agentlib, -agentpath, -javaagent, -Xrunjdwp, and @argfile references. However, the validation is only applied when setting global options via configjava. The jav...

EUVD-2026-65525

NLTK: JVM argument injection bypass via per-call options in the NLTK Stanford wrappers incomplete fix of CVE-2026-12841...

GHSA-6HWM-XVPH-95VM NLTK: Uncontrolled search path when invoking the Graphviz 'dot' binary

Two NLTK sites executed the Graphviz dot program by bare name, so process creation resolved it via the search path — and on Windows via the current working directory — rather than a validated absolute location. An attacker who can place a file named dot where resolution looks the CWD on Windows, ...

EUVD-2026-65226

NLTK: Uncontrolled search path when invoking the Graphviz 'dot' binary...

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. Mitigation Upgrade the nltk...

CVE-2026-81723

A flaw was found in NLTK. This vulnerability, specifically in the XMLCorpusView.readxmlfragment function, allows a remote attacker to cause severe CPU consumption and a denial of service DoS by providing specially crafted, malformed XML corpus files. The flaw occurs because the system repeatedly...

CVE-2026-81727

A flaw was found in NLTK. This vulnerability, a filesystem containment bypass, allows a local attacker with write access to a shared downloader directory to create special links hardlinks that point to files outside the intended installation area. When a package is extracted, these hardlinks can...

CVE-2026-81725

A flaw was found in NLTK, specifically within the Pl196xCorpusReader component. A remote attacker can exploit this by supplying malformed Text Encoding Initiative TEI blocks containing numerous unmatched opening tags. This triggers a regular expression denial of service ReDoS vulnerability, causi...

CVE-2026-81724

A flaw was found in NLTK. This uncontrolled recursion vulnerability in nltk.featstruct.FeatStructReader allows unauthenticated attackers to cause a denial of service. Attackers can achieve this by supplying deeply nested feature-structure input, which can lead to applications crashing when parsin...

CVE-2026-81722

A flaw was found in the nltk PorterStemmer component. A remote attacker could exploit this vulnerability by providing a specially crafted, untrusted token. The inefficient algorithmic complexity in the stemming process, specifically within the isconsonant and measure helper functions, causes...

CVE-2026-63312

A flaw was found in NLTK. This vulnerability, specifically within the StreamBackedCorpusView component, allows an attacker to bypass security enforcement by directly calling builtins.open instead of the intended pathsec.open. By controlling the fileid argument, an attacker can read arbitrary loca...

CVE-2026-71514

A flaw was found in NLTK. This path traversal vulnerability in the CrubadanCorpusReader component allows an attacker, who controls a corpus package, to disclose file contents outside the intended corpus directory. This occurs because a specially crafted input can bypass security checks, leading t...

CVE-2026-62385

A flaw was found in NLTK. This path traversal vulnerability, located in the FramenetCorpusReader and NKJPCorpusReader components, allows an attacker to read arbitrary XML files accessible to the application. This can be achieved by supplying unsafe selectors or poisoned index state, exploiting...