CVE-1999-1577

CVE-1999-1577 is a medium-severity vulnerability in Microsoft Internet Explorer with a CVSS 2.0 base score of 5.1. Its EPSS exploit-prediction score of 19% places it in the 97th percentile, indicating an elevated likelihood of exploitation.

Key facts

Description

Buffer overflow in HHOpen ActiveX control (hhopen.ocx) 1.0.0.1 for Internet Explorer 4.01 and 5 allows remote attackers to execute arbitrary commands via long arguments to the OpenHelp method.

Frequently asked questions

What is CVE-1999-1577?
Buffer overflow in HHOpen ActiveX control (hhopen.ocx) 1.0.0.1 for Internet Explorer 4.01 and 5 allows remote attackers to execute arbitrary commands via long arguments to the OpenHelp method.
How severe is CVE-1999-1577?
CVE-1999-1577 has a CVSS 2.0 base score of 5.1, rated medium severity.
Is CVE-1999-1577 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 19% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-1999-1577?
CVE-1999-1577 primarily affects Microsoft Internet Explorer. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-1999-1577?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-1999-1577 published?
CVE-1999-1577 was published on 1999-10-31 and last updated on 2026-06-16.

References

Affected products (2)

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