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CVE-2020-25708

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use...

7.5 HighFix available

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

1.63%Up 1.1 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service.

Record
CVE-2020-25708
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-369
Updated
2026-11-02
CVE List No score

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service.

Record
CVE-2020-25708
Weakness
CWE-369
Updated
2026-11-02
EUVDEUVD-2020-18363 No score

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service.

Record
EUVD-2020-18363
Updated
2026-11-03
GitHub AdvisoriesGHSA-3xcq-6vjj-wqx7 7.5

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use...

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service.

Record
GHSA-3xcq-6vjj-wqx7
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-369
Updated
2026-11-02
OSVALPINE-CVE-2020-25708 7.5

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service.

Record
ALPINE-CVE-2020-25708
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-03
OSV 7.5

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service.

Record
CVE-2020-25708
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 13 moreShow less
OSVDEBIAN-CVE-2020-25708 7.5

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service.

Record
DEBIAN-CVE-2020-25708
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVRHSA-2021:1811 7.5

Red Hat Security Advisory: libvncserver security update

Record
RHSA-2021:1811
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVRLSA-2021:1811 7.5

Moderate: libvncserver security update

LibVNCServer is a C library that enables you to implement VNC server functionality into own programs.

Security Fix(es):

  • libvncserver: uninitialized memory contents are vulnerable to Information Leak (CVE-2018-21247)

  • libvncserver: buffer overflow in ConnectClientToUnixSock() (CVE-2019-20839)

  • libvncserver: libvncserver/rfbregion.c has a NULL pointer dereference (CVE-2020-14397)

  • libvncserver: libvncclient/rfbproto.c does not limit TextChat size (CVE-2020-14405)

  • libvncserver: libvncserver/rfbserver.c has a divide by zero which could result in DoS (CVE-2020-25708)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the Rocky Linux 8.4 Release Notes linked from the References section.

Record
RLSA-2021:1811
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
OSVUBUNTU-CVE-2020-25708 7.5

A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service.

Record
UBUNTU-CVE-2020-25708
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVALSA-2021:1811 No score

Moderate: libvncserver security update

LibVNCServer is a C library that enables you to implement VNC server functionality into own programs.

Security Fix(es):

  • libvncserver: uninitialized memory contents are vulnerable to Information Leak (CVE-2018-21247)

  • libvncserver: buffer overflow in ConnectClientToUnixSock() (CVE-2019-20839)

  • libvncserver: libvncserver/rfbregion.c has a NULL pointer dereference (CVE-2020-14397)

  • libvncserver: libvncclient/rfbproto.c does not limit TextChat size (CVE-2020-14405)

  • libvncserver: libvncserver/rfbserver.c has a divide by zero which could result in DoS (CVE-2020-25708)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.

Record
ALSA-2021:1811
Updated
2026-11-02
OSVMGASA-2020-0439 No score

Updated vino package fixes a security vulnerability

libvncserver/rfbserver.c from LibVNCServer, which is bundled by vino, has a divide by zero issue which could result in denial of service (CVE-2020-25708).

Record
MGASA-2020-0439
Updated
2026-11-02
OSVopenSUSE-SU-2020:2025-1 No score

Security update for LibVNCServer

This update for LibVNCServer fixes the following issues:

  • CVE-2020-25708 [bsc#1178682], libvncserver/rfbserver.c has a divide by zero which could result in DoS

This update was imported from the SUSE:SLE-15:Update update project.

Record
openSUSE-SU-2020:2025-1
Updated
2026-11-02
OSVopenSUSE-SU-2020:2097-1 No score

Security update for LibVNCServer

This update for LibVNCServer fixes the following issues:

  • CVE-2020-25708 [bsc#1178682], libvncserver/rfbserver.c has a divide by zero which could result in DoS

This update was imported from the SUSE:SLE-15:Update update project.

Record
openSUSE-SU-2020:2097-1
Updated
2026-11-02
OSVopenSUSE-SU-2024:10598-1 No score

LibVNCServer-devel-0.9.13-3.1 on GA media

These are all security issues fixed in the LibVNCServer-devel-0.9.13-3.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2024:10598-1
Updated
2026-11-02
OSVSUSE-SU-2020:14549-1 No score

Security update for LibVNCServer

This update for LibVNCServer fixes the following issues:

  • CVE-2020-25708 [bsc#1178682], libvncserver/rfbserver.c has a divide by zero which could result in DoS
Record
SUSE-SU-2020:14549-1
Updated
2026-11-02
OSVSUSE-SU-2020:3515-1 No score

Security update for LibVNCServer

This update for LibVNCServer fixes the following issues:

  • CVE-2020-25708 [bsc#1178682], libvncserver/rfbserver.c has a divide by zero which could result in DoS
Record
SUSE-SU-2020:3515-1
Updated
2026-11-02
OSVSUSE-SU-2020:3550-1 No score

Security update for LibVNCServer

This update for LibVNCServer fixes the following issues:

  • CVE-2020-25708 [bsc#1178682], libvncserver/rfbserver.c has a divide by zero which could result in DoS
Record
SUSE-SU-2020:3550-1
Updated
2026-11-02
OSVUSN-4636-1 No score

libvncserver, vino vulnerability

It was discovered that LibVNCServer incorrectly handled certain internals. An attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS and Ubuntu 20.04 LTS.

Vino package ships with a LibVNCServer source and all listed releases were affected for this package.

Record
USN-4636-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
libvncserver
Alpine:v3.12
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.13
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.14
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.15
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.16
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.17
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.18
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.19
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.20
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.21
before 0.9.13-r0
0.9.13-r0
Show 70 moreShow less
Affected packages
PackageAffectedFixed
libvncserver
Alpine:v3.22
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.23
before 0.9.13-r0
0.9.13-r0
libvncserver
Alpine:v3.24
before 0.9.13-r0
0.9.13-r0
libvncserver
AlmaLinux:8
From an advisory covering 5 CVEs
before 0.9.11-17.el8
0.9.11-17.el8
libvncserver-devel
AlmaLinux:8
From an advisory covering 5 CVEs
before 0.9.11-17.el8
0.9.11-17.el8
libvncserver
Debian:12
before 0.9.13+dfsg-1
0.9.13+dfsg-1
libvncserver
Debian:13
before 0.9.13+dfsg-1
0.9.13+dfsg-1
libvncserver
Debian:14
before 0.9.13+dfsg-1
0.9.13+dfsg-1
libvncserver
Debian:9
before 0.9.11+dfsg-1.3~deb9u6, plus listed versions
0.9.11+dfsg-10.9.11+dfsg-1+deb9u10.9.11+dfsg-1.10.9.11+dfsg-1.20.9.11+dfsg-1.3~deb9u1
Show 4 moreShow less
0.9.11+dfsg-1.3~deb9u20.9.11+dfsg-1.3~deb9u30.9.11+dfsg-1.3~deb9u40.9.11+dfsg-1.3~deb9u5
0.9.11+dfsg-1.3~deb9u6
libvncserver
Debian:10
From an advisory covering 2 CVEs
before 0.9.11+dfsg-1.3+deb10u5, plus listed versions
0.9.11+dfsg-1.30.9.11+dfsg-1.3+deb10u10.9.11+dfsg-1.3+deb10u20.9.11+dfsg-1.3+deb10u30.9.11+dfsg-1.3+deb10u4
0.9.11+dfsg-1.3+deb10u5
vino
Mageia:7
before 3.22.0-3.3.mga7
3.22.0-3.3.mga7
libvncserver
Red Hat:enterprise_linux:8::appstream
From an advisory covering 5 CVEs
before 0:0.9.11-17.el8
0:0.9.11-17.el8
libvncserver-debuginfo
Red Hat:enterprise_linux:8::appstream
From an advisory covering 5 CVEs
before 0:0.9.11-17.el8
0:0.9.11-17.el8
libvncserver-debugsource
Red Hat:enterprise_linux:8::appstream
From an advisory covering 5 CVEs
before 0:0.9.11-17.el8
0:0.9.11-17.el8
libvncserver-debuginfo
Red Hat:enterprise_linux:8::crb
From an advisory covering 5 CVEs
before 0:0.9.11-17.el8
0:0.9.11-17.el8
libvncserver-debugsource
Red Hat:enterprise_linux:8::crb
From an advisory covering 5 CVEs
before 0:0.9.11-17.el8
0:0.9.11-17.el8
libvncserver-devel
Red Hat:enterprise_linux:8::crb
From an advisory covering 5 CVEs
before 0:0.9.11-17.el8
0:0.9.11-17.el8
libvncserver
Rocky Linux:8
From an advisory covering 5 CVEs
before 0:0.9.11-17.el8
0:0.9.11-17.el8
LibVNCServer
SUSE:Linux Enterprise Point of Sale 11 SP3
before 0.9.1-160.22.1
0.9.1-160.22.1
LibVNCServer
SUSE:Linux Enterprise Server 11 SP4-LTSS
before 0.9.1-160.22.1
0.9.1-160.22.1
LibVNCServer
SUSE:Linux Enterprise Module for Package Hub 15 SP1
before 0.9.10-4.25.1
0.9.10-4.25.1
LibVNCServer
SUSE:Linux Enterprise Module for Package Hub 15 SP2
before 0.9.10-4.25.1
0.9.10-4.25.1
LibVNCServer
SUSE:Linux Enterprise Workstation Extension 15 SP1
before 0.9.10-4.25.1
0.9.10-4.25.1
LibVNCServer
SUSE:Linux Enterprise Workstation Extension 15 SP2
before 0.9.10-4.25.1
0.9.10-4.25.1
LibVNCServer
SUSE:HPE Helion OpenStack 8
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:OpenStack Cloud 7
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:OpenStack Cloud 8
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:OpenStack Cloud 9
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:OpenStack Cloud Crowbar 8
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:OpenStack Cloud Crowbar 9
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server for SAP Applications 12 SP2
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server for SAP Applications 12 SP3
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server for SAP Applications 12 SP4
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Software Development Kit 12 SP5
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server 12 SP2-LTSS
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server 12 SP2-BCL
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server 12 SP3-LTSS
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server 12 SP3-BCL
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server 12 SP4-LTSS
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server 12 SP5
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Linux Enterprise Server for SAP Applications 12 SP5
before 0.9.9-17.34.1
0.9.9-17.34.1
LibVNCServer
SUSE:Enterprise Storage 5
before 0.9.9-17.34.1
0.9.9-17.34.1
tightvnc
Ubuntu:Pro:14.04:LTS
All versions, plus listed versions
1.3.9-6.41.3.9-6.4ubuntu11.3.9-6.5+deb8u1build0.14.04.1~esm1
None known
x11vnc
Ubuntu:14.04:LTS
All versions, plus listed versions
0.9.13-1.1
None known
libvncserver
Ubuntu:16.04:LTS
before 0.9.10+dfsg-3ubuntu0.16.04.6, plus listed versions
0.9.10+dfsg-30.9.10+dfsg-3build10.9.10+dfsg-3ubuntu0.16.04.10.9.10+dfsg-3ubuntu0.16.04.20.9.10+dfsg-3ubuntu0.16.04.30.9.10+dfsg-3ubuntu0.16.04.40.9.10+dfsg-3ubuntu0.16.04.5
0.9.10+dfsg-3ubuntu0.16.04.6
vino
Ubuntu:16.04:LTS
before 3.8.1-0ubuntu9.4, plus listed versions
3.8.1-0ubuntu63.8.1-0ubuntu73.8.1-0ubuntu83.8.1-0ubuntu93.8.1-0ubuntu9.13.8.1-0ubuntu9.23.8.1-0ubuntu9.3
3.8.1-0ubuntu9.4
italc
Ubuntu:16.04:LTS
All versions, plus listed versions
1:2.0.2+dfsg1-31:2.0.2+dfsg1-41:2.0.2+dfsg1-4ubuntu0.1
None known
tightvnc
Ubuntu:16.04:LTS
All versions, plus listed versions
1.3.10-0ubuntu21.3.10-0ubuntu3
None known
libvncserver
Ubuntu:18.04:LTS
before 0.9.11+dfsg-1ubuntu1.4, plus listed versions
0.9.11+dfsg-10.9.11+dfsg-1ubuntu10.9.11+dfsg-1ubuntu1.10.9.11+dfsg-1ubuntu1.20.9.11+dfsg-1ubuntu1.3
0.9.11+dfsg-1ubuntu1.4
vino
Ubuntu:18.04:LTS
before 3.22.0-3ubuntu1.2, plus listed versions
3.8.1-0ubuntu123.22.0-2ubuntu13.22.0-3ubuntu13.22.0-3ubuntu1.1
3.22.0-3ubuntu1.2
italc
Ubuntu:18.04:LTS
All versions, plus listed versions
1:3.0.3+dfsg1-11:3.0.3+dfsg1-21:3.0.3+dfsg1-2build11:3.0.3+dfsg1-2ubuntu11:3.0.3+dfsg1-31:3.0.3+dfsg1-3ubuntu0.1
None known
tightvnc
Ubuntu:18.04:LTS
All versions, plus listed versions
1.3.10-0ubuntu31.3.10-0ubuntu4
None known
libvncserver
Ubuntu:20.04:LTS
before 0.9.12+dfsg-9ubuntu0.3, plus listed versions
0.9.11+dfsg-1.30.9.12+dfsg-3ubuntu30.9.12+dfsg-60.9.12+dfsg-70.9.12+dfsg-80.9.12+dfsg-90.9.12+dfsg-9ubuntu0.10.9.12+dfsg-9ubuntu0.2
0.9.12+dfsg-9ubuntu0.3
vino
Ubuntu:20.04:LTS
before 3.22.0-5ubuntu2.2, plus listed versions
3.22.0-5ubuntu23.22.0-5ubuntu2.1
3.22.0-5ubuntu2.2
tightvnc
Ubuntu:20.04:LTS
All versions, plus listed versions
1.3.10-0ubuntu5
None known
veyon
Ubuntu:20.04:LTS
All versions, plus listed versions
4.2.4+repack1-24.2.5+repack1-14.3.1+repack1-14.3.1+repack1-24.3.1+repack1-2build14.3.1+repack1-2build2
None known
tightvnc
Ubuntu:22.04:LTS
All versions, plus listed versions
1:1.3.10-31:1.3.10-5
None known
veyon
Ubuntu:22.04:LTS
All versions, plus listed versions
4.5.3+repack1-1build14.5.3+repack1-1build2
None known
vino
Ubuntu:22.04:LTS
before 3.22.0-6ubuntu3
3.22.0-6ubuntu3
tightvnc
Ubuntu:24.04:LTS
All versions, plus listed versions
1:1.3.10-71:1.3.10-7build11:1.3.10-7build21:1.3.10-8
None known
veyon
Ubuntu:24.04:LTS
All versions, plus listed versions
4.7.5+repack1-1build24.7.5+repack1-1ubuntu14.7.5+repack1-1ubuntu34.7.5+repack1-1ubuntu44.7.5+repack1-1ubuntu5
None known
vino
Ubuntu:24.04:LTS
before 3.22.0-6ubuntu3
3.22.0-6ubuntu3
tightvnc
Ubuntu:25.10
All versions, plus listed versions
1:1.3.10-91:1.3.10-10
None known
veyon
Ubuntu:25.10
All versions, plus listed versions
4.7.5+repack1-1ubuntu64.7.5+repack1-1ubuntu74.9.7+repack1-1
None known
tightvnc
Ubuntu:26.10
All versions, plus listed versions
1:1.3.10-10build11:1.3.10-11
None known
veyon
Ubuntu:26.10
All versions, plus listed versions
4.9.7+repack1-1build14.9.7+repack1-1.14.9.7+repack1-1.1build14.9.7+repack1-1.1build2
None known
tightvnc
Ubuntu:26.04:LTS
All versions, plus listed versions
1:1.3.10-101:1.3.10-10build1
None known
veyon
Ubuntu:26.04:LTS
All versions, plus listed versions
4.9.7+repack1-14.9.7+repack1-1build1
None known
LibVNCServer
openSUSE:Leap 15.2
before 0.9.10-lp152.9.8.1
0.9.10-lp152.9.8.1
LibVNCServer
openSUSE:Leap 15.1
before 0.9.10-lp151.7.12.1
0.9.10-lp151.7.12.1

History

History
RecordedChangedSources
affected, facts
affected, aliases, referencesOSV
aliases, productsEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-25708 is a high vulnerability (CVSS 7.5) in Libvnc Libvncserver, published November 13, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.63%, the 76th percentile. Fixed in libvncserver 0.9.13-r0.

References

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