CVE-2006-1336: Cross-site scripting vulnerability in calendar.php in ExtCalendar 1.0 and possibly other versions before 2.0 a

This month

MEDIUM 5.0DOWNGRADE

CVE-2006-1336 is a medium-severity flaw (CVSS 5.0) affecting extcalendar. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross-site scripting vulnerability in calendar.php in ExtCalendar 1.0 and possibly other versions before 2.0 allows remote attackers to inject arbitrary web script or HTML via the (1) year, (2) month, (3) next, and (4) prev parameters.

Why this priority

EPSS top 6%: very likely to be exploited
Public exploit reference

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	6.7% (top 6%)
CISA exploited list	No
Published	2006-03-21
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: extcalendar

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

Am I affected?

Timeline

2006-03-21 02:06 UTCPublished CVE record published
2026-06-16 22:22 UTCUpdated Record last modified

extcalendar extcalendar DOWNGRADE

Affected: 1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.0 (Debian / Ubuntu)

apt-cache madison extcalendar sudo apt install extcalendar=<VERSION_BEFORE_1.0> sudo apt-mark hold extcalendar

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

dnf --showduplicates list extcalendar sudo dnf downgrade extcalendar-<VERSION_BEFORE_1.0> sudo dnf versionlock add extcalendar

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: Extcalendar 1.0 - Cross-Site Scripting

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-2006-1336?

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

Is CVE-2006-1336 being exploited?

CVE-2006-1336 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-2006-1336 affect?

CVE-2006-1336 affects extcalendar. Severity is medium (CVSS 5.0). Cross-site scripting vulnerability in calendar.php in ExtCalendar 1.0 and possibly other versions before 2.0 allows remote attackers to inject arbitrary web script or HTML via the (1) year, (2) month, (3) next, and (4) prev parameters.

How urgent is CVE-2006-1336?

Priority 46/100. EPSS top 6%: very likely to be exploited; Public exploit reference

Software pages

PHP vulnerabilities

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References

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