CVE-2026-81727: Improper Link Resolution Before File Access

NLTK versions before 3.10.3 contain a filesystem containment bypass vulnerability in the Downloader.download and Downloader.incrdownload methods that allows attackers to overwrite files outside the install root through pre-existing hardlinks. Attackers with write access to a shared downloader...

CVE-2026-81726: External Control of File Name or Path

NLTK through 3.10.3 contains a path traversal vulnerability in model-artifact APIs that bypass pathsec enforcement by using raw file operations on caller-controlled paths. Attackers can read or write files outside allowed sandbox roots through TransitionParser, AveragedPerceptron, PerceptronTagge...

PT-2026-82622

Name of the Vulnerable Software and Affected Versions NLTK versions prior to 3.10.3 Description A filesystem containment bypass exists in the Downloader.download and Downloader.incr download methods. Attackers with write access to a shared downloader directory can create hardlinks pointing to fil...

PT-2026-82619

Name of the Vulnerable Software and Affected Versions NLTK versions prior to 3.10.3 Description An uncontrolled recursion issue exists in the nltk.featstruct.FeatStructReader class. Unauthenticated attackers can trigger a denial of service by providing deeply nested feature-structure input, such ...

PT-2026-82621

Name of the Vulnerable Software and Affected Versions NLTK versions prior to 3.10.4 Description Path traversal occurs in model-artifact APIs when pathsec is enabled. The issue arises from the use of raw file operations on caller-controlled paths, which allows bypassing pathsec enforcement. This...

PT-2026-82620

Name of the Vulnerable Software and Affected Versions NLTK versions prior to 3.10.3 Description A regular expression denial of service exists in Pl196xCorpusReader. An attacker can cause quadratic CPU consumption by providing malformed TEI Text Encoding Initiative blocks containing numerous...

PT-2026-82617

Name of the Vulnerable Software and Affected Versions nltk PorterStemmer versions prior to 3.10.3 Description The PorterStemmer contains an inefficient-algorithmic-complexity issue that can lead to a denial of service. The is consonant helper function walks backward over trailing 'y' characters o...

PT-2026-82618

Name of the Vulnerable Software and Affected Versions NLTK versions prior to 3.10.3 Description A quadratic CPU exhaustion issue exists in the XMLCorpusView. read xml fragment function. This occurs because the system rescans accumulated XML fragments for every 1 KiB block read. An attacker can...

CVE-2026-81725: Uncontrolled Resource Consumption

NLTK before 3.10.3 contains a regular expression denial of service vulnerability in Pl196xCorpusReader that allows attackers to cause quadratic CPU consumption by supplying malformed TEI blocks with many unmatched opening tags. Attackers can exploit lazy regex patterns in the readblock method...

Linux Distros Unpatched Vulnerability : CVE-2026-81726

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - NLTK through 3.10.3 contains a path traversal vulnerability in model-artifact APIs that bypass pathsec enforcement by using raw file operations on...

Linux Distros Unpatched Vulnerability : CVE-2026-81725

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - NLTK before 3.10.3 contains a regular expression denial of service vulnerability in Pl196xCorpusReader that allows attackers to cause quadratic CPU consumption ...

Linux Distros Unpatched Vulnerability : CVE-2026-81723

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - NLTK versions before 3.10.3 contain a quadratic CPU exhaustion vulnerability in XMLCorpusView.readxmlfragment that rescans accumulated XML fragments on every 1...

Linux Distros Unpatched Vulnerability : CVE-2026-81727

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - NLTK versions before 3.10.3 contain a filesystem containment bypass vulnerability in the Downloader.download and Downloader.incrdownload methods that allows...

Linux Distros Unpatched Vulnerability : CVE-2026-81724

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - NLTK before 3.10.3 contains an uncontrolled recursion vulnerability in nltk.featstruct.FeatStructReader that allows unauthenticated attackers to cause a denial ...

Linux Distros Unpatched Vulnerability : CVE-2026-81722

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - nltk PorterStemmer in versions = 3.10.2 fixed in 3.10.3 contains an inefficient-algorithmic-complexity denial of service in PorterStemmer.stem. The isconsonant...

Duplicate Advisory: ReDoS in nltk.text.Text.findall() via unvalidated user-supplied regular expressions

Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-rrv8-h7p8-rx55. This link is maintained to preserve external references. Original Description NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall and...

GHSA-2RRW-HPQM-36PV Duplicate Advisory: ReDoS in nltk.text.Text.findall() via unvalidated user-supplied regular expressions

Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-rrv8-h7p8-rx55. This link is maintained to preserve external references. Original Description NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall and...

Regular Expression Denial of Service (ReDoS)

Overview nltk is a Natural Language Toolkit NLTK is a Python package for natural language processing. Affected versions of this package are vulnerable to Regular Expression Denial of Service ReDoS in TokenSearcher.findall and Text.findall in nltk/text.py. An attacker can pin a Python worker and...

Regular Expression Denial of Service (ReDoS)

Overview nltk is a Natural Language Toolkit NLTK is a Python package for natural language processing. Affected versions of this package are vulnerable to Regular Expression Denial of Service ReDoS through the tgrepnodeaction path in nltk/tgrep.py. An attacker can pin a CPU core indefinitely by...

PYSEC-2026-3751

NLTK before 3.10.3 contains a regular expression denial of service ReDoS vulnerability in the tgrep module. The tgrepnodeaction function compiles user-supplied regular expressions embedded in /regex/ pattern nodes and executes them via re.search against tree node labels without any validation or...