--- title: "CVE-2018-20748\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-2018-20748?format=md keywords: index, follow --- # CVE-2018-20748 Publication date 30 January 2019 Last updated 11 July 2025 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **9.8 · Critical** [Score breakdown](https://ubuntu.com/security/CVE-2018-20748?format=md#impact-score) Toggle side navigation ## Description LibVNC before 0.9.12 contains multiple heap out-of-bounds write vulnerabilities in libvncclient/rfbproto.c. The fix for CVE-2018-20019 was incomplete. [Read the notes from the security team](https://ubuntu.com/security/CVE-2018-20748?format=md#notes) ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | tightvnc | 26.04 LTS resolute | Needs evaluation | | 25.10 questing | Ignored end of life, was needs-triage | | 25.04 plucky | Ignored end of life, was needs-triage | | 24.10 oracular | Ignored end of life, was needs-triage | | 24.04 LTS noble | Needs evaluation | | 23.10 mantic | Ignored end of life, was needs-triage | | 23.04 lunar | Ignored end of life, was needs-triage | | 22.10 kinetic | Ignored end of life, was needs-triage | | 22.04 LTS jammy | Needs evaluation | | 21.10 impish | Ignored end of life | | 21.04 hirsute | Ignored end of life | | 20.10 groovy | Ignored end of life | | 20.04 LTS focal | Needs evaluation | | 18.04 LTS bionic | Needs evaluation | | 16.04 LTS xenial | Needs evaluation | | 14.04 LTS trusty | Fixed 1.3.9-6.5+deb8u1build0.14.04.1~esm1 Ubuntu Pro | | italc | 26.04 LTS resolute | Not in release | | 25.10 questing | Not in release | | 25.04 plucky | Not in release | | 24.10 oracular | Not in release | | 24.04 LTS noble | Not in release | | 23.10 mantic | Not in release | | 23.04 lunar | Not in release | | 22.10 kinetic | Not in release | | 22.04 LTS jammy | Not in release | | 21.10 impish | Not in release | | 21.04 hirsute | Not in release | | 20.10 groovy | Not in release | | 20.04 LTS focal | Not in release | | 18.04 LTS bionic | Fixed 1:3.0.3+dfsg1-3ubuntu0.1 | | 16.04 LTS xenial | Fixed 1:2.0.2+dfsg1-4ubuntu0.1 | | 14.04 LTS trusty | Not in release | | libvncserver | 26.04 LTS resolute | Not affected | | 25.10 questing | Not affected | | 25.04 plucky | Not affected | | 24.10 oracular | Not affected | | 24.04 LTS noble | Not affected | | 23.10 mantic | Not affected | | 23.04 lunar | Not affected | | 22.10 kinetic | Not affected | | 22.04 LTS jammy | Not affected | | 21.10 impish | Not affected | | 21.04 hirsute | Not affected | | 20.10 groovy | Not affected | | 20.04 LTS focal | Not affected | | 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 | 26.04 LTS resolute | Not affected | | 25.10 questing | Not affected | | 25.04 plucky | Not affected | | 24.10 oracular | Not affected | | 24.04 LTS noble | Not affected | | 23.10 mantic | Not affected | | 23.04 lunar | Not affected | | 22.10 kinetic | Not affected | | 22.04 LTS jammy | Not affected | | 21.10 impish | Not affected | | 21.04 hirsute | Not affected | | 20.10 groovy | Not affected | | 20.04 LTS focal | Not affected | | 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-2018-20748?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) ## Notes --- ### [mdeslaur](https://launchpad.net/~mdeslaur) Further fixes for CVE-2018-20019 ### 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: [c5ba3fe](https://github.com/LibVNC/libvncserver/commit/c5ba3fee85a7ecbbca1df5ffd46d32b92757bc2a) * Upstream: [e34bcbb](https://github.com/LibVNC/libvncserver/commit/e34bcbb759ca5bef85809967a268fdf214c1ad2c) * Upstream: [c2c4b81](https://github.com/LibVNC/libvncserver/commit/c2c4b81e6cb3b485fb1ec7ba9e7defeb889f6ba7) * Upstream: [a64c3b3](https://github.com/LibVNC/libvncserver/commit/a64c3b37af9a6c8f8009d7516874b8d266b42bae) | ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 9.8 · Critical * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Privileges required | None | | User interaction | None | | Scope | Unchanged | | Confidentiality impact | High | | Integrity impact | High | | Availability impact | High | * Scores | Parameter | Value | | --- | --- | | Base score | 9.8 · Critical | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-20748) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-20748) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-20748) * [Debian](https://security-tracker.debian.org/tracker/CVE-2018-20748) ### Related Ubuntu Security Notices (USN) + [USN-3877-1](https://usn.ubuntu.com/USN-3877-1) + LibVNCServer vulnerabilities + 31 January 2019 + [USN-4547-1](https://usn.ubuntu.com/USN-4547-1) + iTALC vulnerabilities + 28 September 2020 + [USN-4587-1](https://usn.ubuntu.com/USN-4587-1) + iTALC vulnerabilities + 20 October 2020 ### Other references *