--- title: "CVE-2026-0847\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2026-0847?format=md keywords: index, follow --- # CVE-2026-0847 Publication date 4 March 2026 Last updated 27 May 2026 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **8.6 · High** [Score breakdown](https://ubuntu.com/security/CVE-2026-0847?format=md#impact-score) Toggle side navigation ## Description A vulnerability in NLTK versions up to and including 3.9.2 allows arbitrary file read via path traversal in multiple CorpusReader classes, including WordListCorpusReader, TaggedCorpusReader, and BracketParseCorpusReader. These classes fail to properly sanitize or validate file paths, enabling attackers to traverse directories and access sensitive files on the server. This issue is particularly critical in scenarios where user-controlled file inputs are processed, such as in machine learning APIs, chatbots, or NLP pipelines. Exploitation of this vulnerability can lead to unauthorized access to sensitive files, including system files, SSH private keys, and API tokens, and may potentially escalate to remote code execution when combined with other vulnerabilities. ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | nltk | 26.04 LTS resolute | Fixed 3.9.2-1ubuntu0.1~esm2 Ubuntu Pro | | 25.10 questing | Ignored end of life, was needed | | 24.04 LTS noble | Fixed 3.8.1-1ubuntu0.1~esm2 Ubuntu Pro | | 22.04 LTS jammy | Fixed 3.7-1ubuntu0.1~esm2 Ubuntu Pro | | 20.04 LTS focal | Fixed 3.4.5-2ubuntu0.1~esm4 Ubuntu Pro | | 18.04 LTS bionic | Fixed 3.2.5-1ubuntu0.1+esm4 Ubuntu Pro | | 16.04 LTS xenial | Fixed 3.1-1ubuntu0.1+esm4 | | 14.04 LTS trusty | Fixed 2.0~b9-0ubuntu4.1~esm6 Ubuntu Pro | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) * [Patch details](https://ubuntu.com/security/CVE-2026-0847?format=md#patch-details) ### Get expanded security coverage with Ubuntu Pro Reduce your average CVE exposure time from 98 days to 1 day with expanded CVE patching, ten-years security maintenance and optional support for the full stack of open-source applications. Free for personal use. [Get Ubuntu Pro](https://ubuntu.com/pro) [30-day free trial](https://ubuntu.com/pro/free-trial) ### Patch details For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) | Package | Patch details | | --- | --- | | nltk | * Upstream: [603e34d](https://github.com/nltk/nltk/commit/603e34d25a2cad4612185ebfa6bc1c0dcfcfb2ab) | ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 8.6 · High * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Privileges required | None | | User interaction | None | | Scope | Unchanged | | Confidentiality impact | High | | Integrity impact | Low | | Availability impact | Low | * Scores | Parameter | Value | | --- | --- | | Base score | 8.6 · High | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-0847) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-0847) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-0847) * [Debian](https://security-tracker.debian.org/tracker/CVE-2026-0847) ### Related Ubuntu Security Notices (USN) + [USN-8302-1](https://usn.ubuntu.com/USN-8302-1) + NLTK vulnerabilities + 25 May 2026 ### Other references * * * * *