CVE-2008-6736: Flat Calendar 1.1 does not properly restrict access to administrative functions, which allows remote attackers

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MEDIUM 6.4DOWNGRADE

CVE-2008-6736 is a medium-severity flaw (CVSS 6.4) affecting flat calendar. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Flat Calendar 1.1 does not properly restrict access to administrative functions, which allows remote attackers to (1) add new events via calAdd.php, as reachable from admin/add.php, or (2) delete events via admin/deleteEvent.php. NOTE: this is only a vulnerability when the administrator does not follow recommendations in the product's security documentation.

Why this priority

Public exploit reference

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

Risk facts

CVSS score	6.4 (Medium)
EPSS exploit chance	2.2% (top 18%)
CISA exploited list	No
Weakness	CWE-264
Published	2009-04-21
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: circulargenius

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

Am I affected?

Timeline

2009-04-21 18:30 UTCPublished CVE record published
2026-06-16 23:02 UTCUpdated Record last modified

circulargenius flat calendar DOWNGRADE

Affected: 1.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.1

1. Check installed version

apt-cache policy flat-calendar || rpm -q flat-calendar || flat-calendar --version

2. No fixed release: DOWNGRADE to a release before 1.1 (Debian / Ubuntu)

apt-cache madison flat-calendar sudo apt install flat-calendar=<VERSION_BEFORE_1.1> sudo apt-mark hold flat-calendar

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

dnf --showduplicates list flat-calendar sudo dnf downgrade flat-calendar-<VERSION_BEFORE_1.1> sudo dnf versionlock add flat-calendar

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: Flat Calendar 1.1 - Multiple Administrative Scripts Authentication Bypass Vulnerabilities

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-2008-6736?

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

Is CVE-2008-6736 being exploited?

CVE-2008-6736 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-2008-6736 affect?

CVE-2008-6736 affects flat calendar. Severity is medium (CVSS 6.4). Flat Calendar 1.1 does not properly restrict access to administrative functions, which allows remote attackers to (1) add new events via calAdd.php, as reachable from admin/add.php, or (2) delete events via admin/deleteEvent.php. NOTE: thi

How urgent is CVE-2008-6736?

Priority 48/100. Public exploit reference

Software pages

PHP vulnerabilities

References

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