# NLTK Project Natural Language Toolkit vulnerabilities Source: https://junglewise.ai/threats/technologies/natural-language-toolkit Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats Updated: 13 November 2026, 03:07 UTC. Rebuilt every hour. Data: https://junglewise.ai/threats/technologies/natural-language-toolkit.json License: CC BY 4.0 with a link back Junglewise Threat Intelligence has tracked 56 vulnerabilities in NLTK Project Natural Language Toolkit: 0 in the last 7 days and 44 in the last 90 days, 6 of them critical and 0 exploited in the wild. The most recent, CVE-2026-109956, was published on 13 October 2026. 1 vulnerability in the last four weeks, up from none in the four before. ## Counts - Last 7 days: 0 - Last 30 days: 0 - Last 90 days: 44 - All time: 56 (6 critical, 0 exploited in the wild) ## About NLTK Project Natural Language Toolkit A suite of libraries and programs for symbolic and statistical natural language processing for the Python programming language. ## Latest NLTK Project Natural Language Toolkit vulnerabilities - [CVE-2026-109956: NLTK WekaClassifier path traversal in model validation](https://junglewise.ai/threats/cve-2026-109956-nltk-through-3-10-3-contains-a-path-traversal-vulnerability-in) (high, CVSS 7, published 13 Oct 2026) - [CVE-2026-12876: NLTK RecursiveDescentParser uncontrolled recursion denial of service](https://junglewise.ai/threats/cve-2026-12876-nltk-recursivedescentparser-uncontrolled-recursion-denial-of) (medium, CVSS 4, published 2 Sep 2026) - [NLTK tgrep regular expression denial of service](https://junglewise.ai/threats/nltk-tgrep-regular-expression-denial-of-service-02fca1b2) (medium, CVSS 5.9, published 31 Aug 2026) - [NLTK path traversal in model-artifact APIs via pathsec bypass](https://junglewise.ai/threats/nltk-path-traversal-in-model-artifact-apis-via-pathsec-bypass-a4651c73) (high, CVSS 7, published 27 Aug 2026) - [NLTK uncontrolled recursion in FeatStructReader denial of service](https://junglewise.ai/threats/nltk-uncontrolled-recursion-in-featstructreader-denial-of-service-e246abcc) (medium, CVSS 5.3, published 27 Aug 2026) - [NLTK Downloader hardlink filesystem containment bypass](https://junglewise.ai/threats/nltk-downloader-hardlink-filesystem-containment-bypass-522cb97d) (high, CVSS 7.1, published 27 Aug 2026) - [NLTK quadratic CPU exhaustion in XMLCorpusView._read_xml_fragment()](https://junglewise.ai/threats/nltk-quadratic-cpu-exhaustion-in-xmlcorpusview-read-xml-fragment-439bc4da) (low, CVSS 3.7, published 27 Aug 2026) - [CVE-2026-81727: NLTK Downloader hardlink traversal in file extraction](https://junglewise.ai/threats/cve-2026-81727-nltk-downloader-hardlink-traversal-in-file-extraction) (high, CVSS 7.1, published 27 Aug 2026) - [CVE-2026-81726: NLTK model-artifact APIs sandbox bypass via path traversal](https://junglewise.ai/threats/cve-2026-81726-nltk-model-artifact-apis-sandbox-bypass-via-path-traversal) (high, CVSS 7, published 27 Aug 2026) - [CVE-2026-81724: NLTK FeatStructReader uncontrolled recursion denial of service](https://junglewise.ai/threats/cve-2026-81724-nltk-featstructreader-uncontrolled-recursion-denial-of-service) (medium, CVSS 5.3, published 27 Aug 2026) - [CVE-2026-81723: NLTK XMLCorpusView quadratic CPU exhaustion](https://junglewise.ai/threats/cve-2026-81723-nltk-xmlcorpusview-quadratic-cpu-exhaustion) (low, CVSS 3.7, published 27 Aug 2026) - [CVE-2026-81722: NLTK PorterStemmer quadratic-time DoS via long runs of 'y'](https://junglewise.ai/threats/cve-2026-81722-nltk-porterstemmer-quadratic-time-dos-via-long-runs-of-y) (high, CVSS 7.5, published 27 Aug 2026) - [NLTK ReDoS in Text.findall() via unvalidated regex](https://junglewise.ai/threats/nltk-redos-in-text-findall-via-unvalidated-regex-70befad1) (high, CVSS 7.5, published 26 Aug 2026) - [CVE-2026-80205: NLTK ReDoS in Text.findall via unvalidated regex](https://junglewise.ai/threats/cve-2026-80205-nltk-redos-in-text-findall-via-unvalidated-regex) (high, CVSS 7.5, published 26 Aug 2026) - [NLTK corpus readers symlink path traversal bypass](https://junglewise.ai/threats/nltk-corpus-readers-symlink-path-traversal-bypass-edf52a38) (medium, CVSS 5.9, published 25 Aug 2026) - [NLTK JVM argument injection in Stanford wrappers via per-call options](https://junglewise.ai/threats/nltk-jvm-argument-injection-in-stanford-wrappers-via-per-call-options-628f3938) (critical, CVSS 9.8, published 25 Aug 2026) - [CVE-2026-79676: NLTK corpus readers symlink boundary bypass](https://junglewise.ai/threats/cve-2026-79676-nltk-corpus-readers-symlink-boundary-bypass) (high, CVSS 5.9, published 25 Aug 2026) - [CVE-2026-79675: NLTK JVM argument injection bypass in Stanford wrappers](https://junglewise.ai/threats/cve-2026-79675-nltk-jvm-argument-injection-bypass-in-stanford-wrappers) (critical, CVSS 9.8, published 25 Aug 2026) - [CVE-2026-79674: NLTK corpus reader sandbox bypass](https://junglewise.ai/threats/cve-2026-79674-nltk-corpus-reader-sandbox-bypass) (high, CVSS 8.2, published 25 Aug 2026) - [NLTK unsafe pickle deserialization in allowlisted loaders](https://junglewise.ai/threats/nltk-unsafe-pickle-deserialization-in-allowlisted-loaders-eeef7a48) (critical, CVSS 9.8, published 25 Aug 2026) - [NLTK pathsec SSRF protection bypass with proxy configured](https://junglewise.ai/threats/nltk-pathsec-ssrf-protection-bypass-with-proxy-configured-e731f278) (high, CVSS 7.5, published 25 Aug 2026) - [NLTK unsafe pickle deserialization in TransitionParser](https://junglewise.ai/threats/nltk-unsafe-pickle-deserialization-in-transitionparser-672e8ed3) (critical, CVSS 9.6, published 25 Aug 2026) - [NLTK entity-expansion denial of service via ElementTree XML parsing](https://junglewise.ai/threats/nltk-entity-expansion-denial-of-service-via-elementtree-xml-parsing-e2038a9e) (high, CVSS 7.5, published 25 Aug 2026) - [CVE-2026-78683: NLTK unsafe pickle deserialization in TransitionParser](https://junglewise.ai/threats/cve-2026-78683-nltk-unsafe-pickle-deserialization-in-transitionparser) (critical, CVSS 9.6, published 25 Aug 2026) - [CVE-2026-78682: NLTK pathsec SSRF bypass with HTTP proxy](https://junglewise.ai/threats/cve-2026-78682-nltk-pathsec-ssrf-bypass-with-http-proxy) (high, CVSS 7.5, published 25 Aug 2026) ## Most severe NLTK Project Natural Language Toolkit vulnerabilities - [CVE-2025-14009: NLTK Zip Slip remote code execution in downloader component](https://junglewise.ai/threats/cve-2025-14009-nltk-zip-slip-remote-code-execution-in-downloader-component) (critical, CVSS 10, published 18 Feb 2026) - [CVE-2026-79675: NLTK JVM argument injection bypass in Stanford wrappers](https://junglewise.ai/threats/cve-2026-79675-nltk-jvm-argument-injection-bypass-in-stanford-wrappers) (critical, CVSS 9.8, published 25 Aug 2026) - [NLTK JVM argument injection in Stanford wrappers via per-call options](https://junglewise.ai/threats/nltk-jvm-argument-injection-in-stanford-wrappers-via-per-call-options-628f3938) (critical, CVSS 9.8, published 25 Aug 2026) - [NLTK unsafe pickle deserialization in allowlisted loaders](https://junglewise.ai/threats/nltk-unsafe-pickle-deserialization-in-allowlisted-loaders-eeef7a48) (critical, CVSS 9.8, published 25 Aug 2026) - [CVE-2026-78683: NLTK unsafe pickle deserialization in TransitionParser](https://junglewise.ai/threats/cve-2026-78683-nltk-unsafe-pickle-deserialization-in-transitionparser) (critical, CVSS 9.6, published 25 Aug 2026) - [NLTK unsafe pickle deserialization in TransitionParser](https://junglewise.ai/threats/nltk-unsafe-pickle-deserialization-in-transitionparser-672e8ed3) (critical, CVSS 9.6, published 25 Aug 2026) - [CVE-2026-71513: NLTK AllowlistUnpickler dotted-name validation bypass](https://junglewise.ai/threats/cve-2026-71513-nltk-allowlistunpickler-dotted-name-validation-bypass) (high, CVSS 8.8, published 22 Aug 2026) - [CVE-2026-0847: NLTK path traversal in CorpusReader classes](https://junglewise.ai/threats/cve-2026-0847-nltk-path-traversal-in-corpusreader-classes) (high, CVSS 8.6, published 4 Mar 2026) - [CVE-2026-0846: NLTK arbitrary file read in nltk.util.filestring](https://junglewise.ai/threats/cve-2026-0846-nltk-arbitrary-file-read-in-nltk-util-filestring) (high, CVSS 8.6, published 9 Mar 2026) - [CVE-2026-12075: NLTK DNS-rebinding SSRF filter bypass in pathsec.urlopen](https://junglewise.ai/threats/cve-2026-12075-nltk-dns-rebinding-ssrf-filter-bypass-in-pathsec-urlopen) (high, CVSS 8.6, published 31 Jul 2026) ## Vulnerabilities per week 1 vulnerability in the last four weeks, up from none in the four before. | Week of | Vulns | Critical | Exploited | | --- | --- | --- | --- | | 17 Aug 2026 | 18 | 0 | 0 | | 24 Aug 2026 | 23 | 5 | 0 | | 31 Aug 2026 | 2 | 0 | 0 | | 7 Sep 2026 | 0 | 0 | 0 | | 14 Sep 2026 | 0 | 0 | 0 | | 21 Sep 2026 | 0 | 0 | 0 | | 28 Sep 2026 | 0 | 0 | 0 | | 5 Oct 2026 | 0 | 0 | 0 | | 12 Oct 2026 | 1 | 0 | 0 | | 19 Oct 2026 | 0 | 0 | 0 | | 26 Oct 2026 | 0 | 0 | 0 | | 2 Nov 2026 | 0 | 0 | 0 | | 9 Nov 2026 | 0 | 0 | 0 | ## Sources NVD, GitHub Security Advisories, OSV, the CISA Known Exploited Vulnerabilities catalog, FIRST EPSS and vendor advisories. Rebuilt every hour. Cite as: Junglewise Threat Intelligence, "NLTK Project Natural Language Toolkit vulnerabilities", https://junglewise.ai/threats/technologies/natural-language-toolkit, 13 November 2026.