CVE-2008-4770: The CMsgReader::readRect function in the VNC Viewer component in RealVNC VNC Free Edition 4.0 through 4.1.2, E

This month

HIGH 10.0DOWNGRADE

CVE-2008-4770 is a high-severity flaw (CVSS 10.0) affecting realvnc. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The CMsgReader::readRect function in the VNC Viewer component in RealVNC VNC Free Edition 4.0 through 4.1.2, Enterprise Edition E4.0 through E4.4.2, and Personal Edition P4.0 through P4.4.2 allows remote VNC servers to execute arbitrary code via crafted RFB protocol data, related to "encoding type."

Why this priority

Critical severity
EPSS top 9%: very likely to be exploited

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	10.0 (High)
EPSS exploit chance	4.1% (top 9%)
CISA exploited list	No
Weakness	CWE-20
Published	2009-01-16
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: realvnc

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2009-01-16 21:30 UTCPublished CVE record published
2026-06-16 22:58 UTCUpdated Record last modified

realvnc realvnc DOWNGRADE

Affected: 4.0 · 4.1.2 · 4.4.2 · e4.0 · p4.0 · p4.4.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.0 (Debian / Ubuntu)

apt-cache madison realvnc sudo apt install realvnc=<VERSION_BEFORE_4.0> sudo apt-mark hold realvnc

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list realvnc sudo dnf downgrade realvnc-<VERSION_BEFORE_4.0> sudo dnf versionlock add realvnc

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2008-4770?

realvnc: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2008-4770 being exploited?

CVE-2008-4770 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-2008-4770 affect?

CVE-2008-4770 affects realvnc. Severity is high (CVSS 10.0). The CMsgReader::readRect function in the VNC Viewer component in RealVNC VNC Free Edition 4.0 through 4.1.2, Enterprise Edition E4.0 through E4.4.2, and Personal Edition P4.0 through P4.4.2 allows remote VNC servers to execute arbitrary cod

How urgent is CVE-2008-4770?

Priority 58/100. Critical severity; EPSS top 9%: very likely to be exploited

Related CVEs

CVE-2013-6886 HIGH 7.2 DOWNGRADE RealVNC VNC 5.0.6 on Mac OS X, Linux, and UNIX allows local users to gain privileges via a crafted argument to
CVE-2006-2369 HIGH 7.5 DOWNGRADE RealVNC 4.1.1, and other products that use RealVNC such as AdderLink IP and Cisco CallManager, allows remote a
CVE-2004-1750 MEDIUM 5.0 DOWNGRADE RealVNC 4.0 and earlier allows remote attackers to cause a denial of service (crash) via a large number of con

References

← Back to latest CVEs