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.
Conclusion & alert: CVE-2005-4840 is rated Moderate Risk (55.2/100): CVSS Medium severity, with high exploitation likelihood (EPSS 32.76%, 97th percentile). Core evidence: EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +4.11% over the last day, indicating growing attacker interest. Mandatory action: High exploitation likelihood—assess exposure and prioritize remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-03-18 | 28.65% | 32.76% | +4.11% |
| 2 | 2026-01-24 | 28.30% | 28.65% | +0.35% |
| 3 | 2025-03-30 | — | 28.30% | — |
Full EPSS history (17 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 4.3 | 2.0 | MEDIUM |
|
8.6 | 2.9 | [email protected] |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| microsoft | outlook_express_book_control | — | cpe:2.3:a:microsoft:outlook_express_book_control:*:*:*:*:*:*:*:* |