CVE-2014-6053: The rfbProcessClientNormalMessage function in libvncserver/rfbserver.c in LibVNCServer 0.9.9 and earlier does

Q: How do I fix CVE-2014-6053?

libvncserver: upgrade to newer than 0.9.9; ubuntu linux: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2014-6053 being exploited?

CVE-2014-6053 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2014-6053 affect?

CVE-2014-6053 affects libvncserver, ubuntu linux, debian linux. Severity is medium (CVSS 5.0). The rfbProcessClientNormalMessage function in libvncserver/rfbserver.c in LibVNCServer 0.9.9 and earlier does not properly handle attempts to send a large amount of ClientCutText data, which allows remote attackers to cause a denial of serv

Q: How urgent is CVE-2014-6053?

Priority 46/100. EPSS top 6%: very likely to be exploited; On your watchlist

This month

MEDIUM 5.0WATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2014-6053 is a medium-severity flaw (CVSS 5.0) affecting libvncserver, ubuntu linux, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The rfbProcessClientNormalMessage function in libvncserver/rfbserver.c in LibVNCServer 0.9.9 and earlier does not properly handle attempts to send a large amount of ClientCutText data, which allows remote attackers to cause a denial of service (memory consumption or daemon crash) via a crafted message that is processed by using a single unchecked malloc.

Why this priority

EPSS top 6%: very likely to be exploited
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	7.3% (top 6%)
CISA exploited list	No
Weakness	CWE-19
Published	2014-12-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: canonical · debian · libvncserver

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2014-12-15 18:59 UTCPublished CVE record published
2026-06-17 00:12 UTCUpdated Record last modified

libvncserver libvncserver UPGRADE

Affected: <= 0.9.9

Fixed in: newer than 0.9.9

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy libvncserver || rpm -q libvncserver || libvncserver --version

2. UPGRADE to newer than 0.9.9 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libvncserver

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libvncserver

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

canonical ubuntu linux MITIGATE

Affected: 12.04 · 14.04

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.04

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

debian debian linux MITIGATE

Affected: 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2014-6053?

libvncserver: upgrade to newer than 0.9.9; ubuntu linux: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2014-6053 being exploited?

CVE-2014-6053 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2014-6053 affect?

CVE-2014-6053 affects libvncserver, ubuntu linux, debian linux. Severity is medium (CVSS 5.0). The rfbProcessClientNormalMessage function in libvncserver/rfbserver.c in LibVNCServer 0.9.9 and earlier does not properly handle attempts to send a large amount of ClientCutText data, which allows remote attackers to cause a denial of serv

How urgent is CVE-2014-6053?

Priority 46/100. EPSS top 6%: very likely to be exploited; On your watchlist

Software pages

Ubuntu vulnerabilities · Debian vulnerabilities

Related CVEs

CVE-2026-32854 HIGH 7.5 UPGRADE LibVNCServer versions 0.9.15 and prior (fixed in commit dc78dee) contain null pointer dereference vulnerabilit
CVE-2026-32853 HIGH 8.1 UPGRADE LibVNCServer versions 0.9.15 and prior (fixed in commit 009008e) contain a heap out-of-bounds read vulnerabili
CVE-2020-29260 HIGH 7.5 DOWNGRADE MITIGATE libvncclient v0.9.13 was discovered to contain a memory leak via the function rfbClientCleanup().
CVE-2020-25708 HIGH 7.5 DOWNGRADE MITIGATE A divide by zero issue was found to occur in libvncserver-0.9.12
CVE-2020-14405 MEDIUM 6.5 UPGRADE MITIGATE An issue was discovered in LibVNCServer before 0.9.13

References

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