---
title: "CVE-2026-0848\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-2026-0848?format=md
keywords: index, follow
---

# CVE-2026-0848

Publication date 5 March 2026

Last updated 27 May 2026

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**10.0 · Critical**

[Score breakdown](https://ubuntu.com/security/CVE-2026-0848?format=md#impact-score)

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## Description

NLTK versions <=3.9.2 are vulnerable to arbitrary code execution due to
improper input validation in the StanfordSegmenter module. The module
dynamically loads external Java .jar files without verification or
sandboxing. An attacker can supply or replace the JAR file, enabling the
execution of arbitrary Java bytecode at import time. This vulnerability can
be exploited through methods such as model poisoning, MITM attacks, or
dependency poisoning, leading to remote code execution. The issue arises
from the direct execution of the JAR file via subprocess with unvalidated
classpath input, allowing malicious classes to execute when loaded by the
JVM.

## 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 | Not affected |
| 14.04 LTS trusty | Not affected |

---

* [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-2026-0848?format=md#patch-details)

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### 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:   [27fab63](https://github.com/nltk/nltk/commit/27fab63c5b7689a125feb282958f630ced3a4f77) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

10.0 · Critical

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Changed |
  | Confidentiality impact | High |
  | Integrity impact | High |
  | Availability impact | High |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 10.0 · Critical |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-0848)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-0848)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-0848)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-0848)

### Related Ubuntu Security Notices (USN)

+ [USN-8302-1](https://usn.ubuntu.com/USN-8302-1)
+ NLTK vulnerabilities
+ 25 May 2026

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-0848>
* <https://huntr.com/bounties/08b109bb-ac24-403f-9422-1c246ce60202>
* <https://github.com/nltk/nltk/pull/3477>
* <https://github.com/nltk/nltk/commit/27fab63c5b7689a125feb282958f630ced3a4f77>