CVE-2006-6721: Multiple cross-site scripting (XSS) vulnerabilities in shout.php in Knusperleicht ShoutBox 2.6 allow remote at

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MEDIUM 6.8DOWNGRADE

CVE-2006-6721 is a medium-severity flaw (CVSS 6.8) affecting shoutbox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Multiple cross-site scripting (XSS) vulnerabilities in shout.php in Knusperleicht ShoutBox 2.6 allow remote attackers to inject arbitrary web script or HTML via the (1) sbNick or (2) sbKommentar parameter.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	6.8 (Medium)
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Published	2006-12-23
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: knusperleicht

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

Am I affected?

Timeline

2006-12-23 11:28 UTCPublished CVE record published
2026-06-16 22:33 UTCUpdated Record last modified

knusperleicht shoutbox DOWNGRADE

Affected: 2.6

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.6

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.6 (Debian / Ubuntu)

apt-cache madison shoutbox sudo apt install shoutbox=<VERSION_BEFORE_2.6> sudo apt-mark hold shoutbox

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

dnf --showduplicates list shoutbox sudo dnf downgrade shoutbox-<VERSION_BEFORE_2.6> sudo dnf versionlock add shoutbox

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: Knusperleicht Shoutbox 2.6 - 'Shout.php' HTML Injection

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-2006-6721?

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

Is CVE-2006-6721 being exploited?

CVE-2006-6721 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-2006-6721 affect?

CVE-2006-6721 affects shoutbox. Severity is medium (CVSS 6.8). Multiple cross-site scripting (XSS) vulnerabilities in shout.php in Knusperleicht ShoutBox 2.6 allow remote attackers to inject arbitrary web script or HTML via the (1) sbNick or (2) sbKommentar parameter.

How urgent is CVE-2006-6721?

Priority 49/100. Public exploit reference

Software pages

PHP vulnerabilities

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References

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