How severe is CVE-2005-4840?

CVE-2005-4840 has a CVSS 2.0 base score of 4.3, rated medium severity.

Is CVE-2005-4840 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 12% (96th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2005-4840?

CVE-2005-4840 affects Microsoft Outlook Express Book Control. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2005-4840?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2005-4840 published?

CVE-2005-4840 was published on 2005-12-31 and last updated on 2026-06-16.

CVE-2005-4840

CVE-2005-4840 is a medium-severity vulnerability in Microsoft Outlook Express Book Control with a CVSS 2.0 base score of 4.3. Its EPSS exploit-prediction score of 12% places it in the 96th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-119.

Key facts

Severity: Medium (CVSS 2.0 base score 4.3)
EPSS exploit prediction: 12% (96th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-119
Affected product: Microsoft Outlook Express Book Control
Published: 2005-12-31
Last modified: 2026-06-16

Description

The Outlook Express Address Book control, when using Internet Explorer 6, allows remote attackers to cause a denial of service (NULL dereference and browser crash) by creating the OutlookExpress.AddressBook COM object, which is not intended for use within Internet Explorer.

Frequently asked questions

What is CVE-2005-4840?: The Outlook Express Address Book control, when using Internet Explorer 6, allows remote attackers to cause a denial of service (NULL dereference and browser crash) by creating the OutlookExpress.AddressBook COM object, which is not intended for use within Internet Explorer.
How severe is CVE-2005-4840?: CVE-2005-4840 has a CVSS 2.0 base score of 4.3, rated medium severity.
Is CVE-2005-4840 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 12% (96th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2005-4840?: CVE-2005-4840 affects Microsoft Outlook Express Book Control. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2005-4840?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2005-4840 published?: CVE-2005-4840 was published on 2005-12-31 and last updated on 2026-06-16.

References

Affected products (1)

cpe:2.3:a:microsoft:outlook_express_book_control:*:*:*:*:*:*:*:*

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