CVE-2006-2369: RealVNC 4.1.1, and other products that use RealVNC such as AdderLink IP and Cisco CallManager, allows remote a

Q: How do I fix CVE-2006-2369?

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

Q: Is CVE-2006-2369 being exploited?

CVE-2006-2369 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-2006-2369 affect?

CVE-2006-2369 affects realvnc. Severity is high (CVSS 7.5). RealVNC 4.1.1, and other products that use RealVNC such as AdderLink IP and Cisco CallManager, allows remote attackers to bypass authentication via a request in which the client specifies an insecure security type such as "Type 1 - None", w

Q: How urgent is CVE-2006-2369?

Priority 56/100. High severity; EPSS top 1%: very likely to be exploited; Public exploit reference

This week

HIGH 7.5DOWNGRADE

CVE-2006-2369 is a high-severity flaw (CVSS 7.5) affecting realvnc. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

RealVNC 4.1.1, and other products that use RealVNC such as AdderLink IP and Cisco CallManager, allows remote attackers to bypass authentication via a request in which the client specifies an insecure security type such as "Type 1 - None", which is accepted even if it is not offered by the server, as originally demonstrated using a long password.

Why this priority

High severity
EPSS top 1%: very likely to be exploited
Public exploit reference

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

Risk facts

CVSS score	7.5 (High)
EPSS exploit chance	92.4% (top 1%)
CISA exploited list	No
Weakness	CWE-287
Published	2006-05-15
Last modified	2026-06-16

Publisher (CNA): Red Hat, Inc. · Vendor: vnc

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

Am I affected?

Timeline

2006-05-15 16:06 UTCPublished CVE record published
2026-06-16 22:24 UTCUpdated Record last modified

vnc realvnc DOWNGRADE

Affected: 4.1.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.1.1

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 4.1.1 (Debian / Ubuntu)

apt-cache madison realvnc sudo apt install realvnc=<VERSION_BEFORE_4.1.1> sudo apt-mark hold realvnc

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

dnf --showduplicates list realvnc sudo dnf downgrade realvnc-<VERSION_BEFORE_4.1.1> 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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: RealVNC 4.1.0 < 4.1.1 - VNC Null Authentication Bypass
Exploit-DB: RealVNC 4.1.0 < 4.1.1 - VNC Null Authentication Bypass (Metasploit)
Exploit-DB: RealVNC - Authentication Bypass (Metasploit)
Exploit-DB: RealVNC 4.1.0/4.1.1 - Authentication Bypass
Metasploit: RealVNC NULL Authentication Mode Bypass
Metasploit: VNC Authentication None Detection

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-2006-2369?

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

Is CVE-2006-2369 being exploited?

CVE-2006-2369 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-2006-2369 affect?

CVE-2006-2369 affects realvnc. Severity is high (CVSS 7.5). RealVNC 4.1.1, and other products that use RealVNC such as AdderLink IP and Cisco CallManager, allows remote attackers to bypass authentication via a request in which the client specifies an insecure security type such as "Type 1 - None", w

How urgent is CVE-2006-2369?

Priority 56/100. High severity; EPSS top 1%: very likely to be exploited; Public exploit reference

Software pages

Cisco vulnerabilities

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References

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