CVE-2011-3780: PHP iCalendar 2.4 allows remote attackers to obtain sensitive information via a direct request to a .php file,

Routine

MEDIUM 5.0DOWNGRADE

CVE-2011-3780 is a medium-severity flaw (CVSS 5.0) affecting php icalendar. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

PHP iCalendar 2.4 allows remote attackers to obtain sensitive information via a direct request to a .php file, which reveals the installation path in an error message, as demonstrated by rss/rss_common.php and certain other files.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	1.2% (top 31%)
CISA exploited list	No
Weakness	CWE-200
Published	2011-09-24
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: phpicalendar

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

Am I affected?

Timeline

2011-09-24 00:55 UTCPublished CVE record published
2026-06-16 23:33 UTCUpdated Record last modified

phpicalendar php icalendar DOWNGRADE

Affected: 2.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.4

1. Check installed version

apt-cache policy php-icalendar || rpm -q php-icalendar || php-icalendar --version

2. No fixed release: DOWNGRADE to a release before 2.4 (Debian / Ubuntu)

apt-cache madison php-icalendar sudo apt install php-icalendar=<VERSION_BEFORE_2.4> sudo apt-mark hold php-icalendar

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

dnf --showduplicates list php-icalendar sudo dnf downgrade php-icalendar-<VERSION_BEFORE_2.4> sudo dnf versionlock add php-icalendar

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-2011-3780?

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

Is CVE-2011-3780 being exploited?

CVE-2011-3780 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-2011-3780 affect?

CVE-2011-3780 affects php icalendar. Severity is medium (CVSS 5.0). PHP iCalendar 2.4 allows remote attackers to obtain sensitive information via a direct request to a .php file, which reveals the installation path in an error message, as demonstrated by rss/rss_common.php and certain other files.

How urgent is CVE-2011-3780?

Priority 35/100. No elevated risk signals yet.

Software pages

PHP vulnerabilities

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References

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