---
title: "CVE-2018-6307\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-2018-6307?format=md
keywords: index, follow
---

# CVE-2018-6307

Publication date 19 December 2018

Last updated 25 August 2025

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**8.1 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2018-6307?format=md#impact-score)

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## Description

LibVNC before commit ca2a5ac02fbbadd0a21fabba779c1ea69173d10b contains heap
use-after-free vulnerability in server code of file transfer extension that
can result remote code execution.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| libvncserver | 19.04 disco | Not affected |
| 18.10 cosmic | Fixed 0.9.11+dfsg-1.1ubuntu0.1 |
| 18.04 LTS bionic | Fixed 0.9.11+dfsg-1ubuntu1.1 |
| 16.04 LTS xenial | Fixed 0.9.10+dfsg-3ubuntu0.16.04.3 |
| 14.04 LTS trusty | Fixed 0.9.9+dfsg-1ubuntu1.4 |
| x11vnc | 19.04 disco | Not affected |
| 18.10 cosmic | Ignored end of life |
| 18.04 LTS bionic | Not affected |
| 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-2018-6307?format=md#patch-details)

### 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 |
| --- | --- |
| libvncserver | * Upstream:   [ca2a5ac](https://github.com/LibVNC/libvncserver/commit/ca2a5ac02fbbadd0a21fabba779c1ea69173d10b) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

8.1 · High

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 8.1 · High |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-6307)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-6307)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-6307)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2018-6307)

### Related Ubuntu Security Notices (USN)

+ [USN-3877-1](https://usn.ubuntu.com/USN-3877-1)
+ LibVNCServer vulnerabilities
+ 31 January 2019

### Other references

* <https://ics-cert.kaspersky.com/advisories/klcert-advisories/2018/12/19/klcert-18-026-libvnc-heap-use-after-free/>
* <https://www.cve.org/CVERecord?id=CVE-2018-6307>