How severe is CVE-2008-5840?

CVE-2008-5840 has a CVSS 2.0 base score of 7.5, rated high severity.

Is CVE-2008-5840 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2008-5840?

CVE-2008-5840 primarily affects Phpicalendar. In total, 17 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2008-5840?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2008-5840 published?

CVE-2008-5840 was published on 2009-01-05 and last updated on 2026-06-16.

CVE-2008-5840

CVE-2008-5840 is a high-severity vulnerability in Phpicalendar with a CVSS 2.0 base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-264.

Key facts

Severity: High (CVSS 2.0 base score 7.5)
EPSS exploit prediction: 3% (86th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-264
Affected product: Phpicalendar
Published: 2009-01-05
Last modified: 2026-06-16

Description

PHP iCalendar 2.24 and earlier allows remote attackers to bypass authentication by setting the phpicalendar and phpicalendar_login cookies to 1.

Frequently asked questions

What is CVE-2008-5840?: PHP iCalendar 2.24 and earlier allows remote attackers to bypass authentication by setting the phpicalendar and phpicalendar_login cookies to 1.
How severe is CVE-2008-5840?: CVE-2008-5840 has a CVSS 2.0 base score of 7.5, rated high severity.
Is CVE-2008-5840 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2008-5840?: CVE-2008-5840 primarily affects Phpicalendar. In total, 17 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2008-5840?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2008-5840 published?: CVE-2008-5840 was published on 2009-01-05 and last updated on 2026-06-16.

References

Affected products (17)

cpe:2.3:a:phpicalendar:phpicalendar:*:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:0.7:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:0.8:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:0.9:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:0.9.5:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:1.0:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:1.1:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:2.0:beta:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:2.0.1:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:2.0c:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:2.1:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:2.2:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:2.21:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:2.22:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:2.23:*:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar:2.23:rc1:*:*:*:*:*:*
cpe:2.3:a:phpicalendar:phpicalendar2.0:alpha_test:*:*:*:*:*:*:*

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