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CVE-1999-1577

31
FAUCET Score

CVE-1999-1577 describes a buffer overflow vulnerability in the HHOpen ActiveX control (hhopen.ocx) version 1.0.0.1, affecting Microsoft Internet Explorer 4.01 and 5. This flaw allows remote attackers to execute arbitrary commands by providing excessively long arguments to the OpenHelp method. Rated Medium severity with a CVSS score of 5.1, it requires high attack complexity but can lead to partial compromise of confidentiality, integrity, and availability. While not listed in CISA's KEV catalog and lacking Metasploit or Nuclei modules, exploit code is publicly available via ExploitDB, though there is no evidence of active exploitation or significant community discussion.

Impacted Technologies

VendorProductVersion(s)CPE
4.0.1CPE matchmatch criteria
cpe:2.3:a:microsoft:internet_explorer:4.0.1:*:*:*:*:*:*:*
5.0CPE matchmatch criteria
cpe:2.3:a:microsoft:internet_explorer:5.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

5.1MEDIUM

AV:N/AC:H/Au:N/C:P/I:P/A:P

Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
Access Vector
NETWORK
Access Complexity
HIGH
Authentication
NONE
Exploitability Score
4.9
Impact Score
6.4
CvssVersion
2.0

Exploit Intelligence

EPSS Score
19.49%
Probability of exploitation in next 30 days
EPSS Percentile
97.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
ExploitDB: EDB-19521 · Sep 27, 1999
This CVE's current EPSS score of 0.1949 is in the 97th percentile among its peer group of 19,958 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

exchange.xforce.ibmcloud.com / vulnerabilities/3314
kb.cert.org / vuls/id/29795
US Government Resource
securityfocus.com / archive/1/28719
securityfocus.com / bid/669