{"id":"UBUNTU-CVE-2026-33231","details":"NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, `nltk.app.wordnet_app` allows unauthenticated remote shutdown of the local WordNet Browser HTTP server when it is started in its default mode. A simple `GET /SHUTDOWN%20THE%20SERVER` request causes the process to terminate immediately via `os._exit(0)`, resulting in a denial of service. Commit bbaae83db86a0f49e00f5b0db44a7254c268de9b patches the issue.","modified":"2026-06-30T18:16:15.092361010Z","published":"2026-03-20T23:16:00Z","related":["USN-8302-1"],"upstream":["CVE-2026-33231"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-33231"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-33231"},{"type":"REPORT","url":"https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b"},{"type":"REPORT","url":"https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-8302-1"}],"affected":[{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-infra-legacy%2Ftrusty"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0~b9-0ubuntu4.1~esm6"}]}],"versions":["2.0~b9-0ubuntu4","2.0~b9-0ubuntu4.1~esm2","2.0~b9-0ubuntu4.1~esm4","2.0~b9-0ubuntu4.1~esm5"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro","binaries":[{"binary_name":"python-nltk","binary_version":"2.0~b9-0ubuntu4.1~esm6"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33231.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1-1ubuntu0.1+esm4"}]}],"versions":["3.0.4-1","3.0.5-1","3.1-1","3.1-1ubuntu0.1","3.1-1ubuntu0.1+esm1","3.1-1ubuntu0.1+esm2","3.1-1ubuntu0.1+esm3"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro","binaries":[{"binary_name":"python-nltk","binary_version":"3.1-1ubuntu0.1+esm4"},{"binary_name":"python3-nltk","binary_version":"3.1-1ubuntu0.1+esm4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33231.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.5-1ubuntu0.1+esm4"}]}],"versions":["3.2.4-1","3.2.5-1","3.2.5-1ubuntu0.1","3.2.5-1ubuntu0.1+esm1","3.2.5-1ubuntu0.1+esm2","3.2.5-1ubuntu0.1+esm3"],"ecosystem_specific":{"binaries":[{"binary_name":"python-nltk","binary_version":"3.2.5-1ubuntu0.1+esm4"},{"binary_version":"3.2.5-1ubuntu0.1+esm4","binary_name":"python3-nltk"}],"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33231.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.4.5-2ubuntu0.1~esm4"}]}],"versions":["3.4.5-1","3.4.5-2","3.4.5-2ubuntu0.1~esm1","3.4.5-2ubuntu0.1~esm2","3.4.5-2ubuntu0.1~esm3"],"ecosystem_specific":{"binaries":[{"binary_version":"3.4.5-2ubuntu0.1~esm4","binary_name":"python3-nltk"}],"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33231.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:22.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fjammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.7-1ubuntu0.1~esm2"}]}],"versions":["3.5-1","3.6.5-1","3.6.7-1","3.7-1","3.7-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-nltk","binary_version":"3.7-1ubuntu0.1~esm2"}],"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33231.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:24.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fnoble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.8.1-1ubuntu0.1~esm2"}]}],"versions":["3.8.1-1","3.8.1-1ubuntu0.1~esm1"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro","binaries":[{"binary_name":"python3-nltk","binary_version":"3.8.1-1ubuntu0.1~esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33231.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.9.1-2"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-nltk","binary_version":"3.9.1-2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33231.json"}},{"package":{"name":"nltk","ecosystem":"Ubuntu:Pro:26.04:LTS","purl":"pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fresolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.9.2-1ubuntu0.1~esm2"}]}],"versions":["3.9.1-2","3.9.1-2build1","3.9.2-1","3.9.2-1ubuntu0.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_version":"3.9.2-1ubuntu0.1~esm2","binary_name":"python3-nltk"}],"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33231.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}