PatchTheCVECVE-2000-0991: Buffer overflow in Hilgraeve, Inc
CVE-2000-0991 is a high-severity flaw (CVSS 7.5) affecting hyperterminal. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Buffer overflow in Hilgraeve, Inc. HyperTerminal client on Windows 98, ME, and 2000 allows remote attackers to execute arbitrary commands via a long telnet URL, aka the "HyperTerminal Buffer Overflow" vulnerability.
Why this priority
- High severity
- EPSS top 4%: very likely to be exploited
- Public exploit reference
A fixed release or distro patch exists.
Risk facts
| CVSS score | 7.5 (High) |
| EPSS exploit chance | 9.7% (top 4%) |
| CISA exploited list | No |
| Published | 2000-12-19 |
| Last modified | 2026-09-23 |
Last updated 2026-09-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Public exploits and detection
Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2000-0991?
hyperterminal: upgrade to newer than 6.0. Exact commands for each OS are on this page.
Is CVE-2000-0991 being exploited?
CVE-2000-0991 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2000-0991 affect?
CVE-2000-0991 affects hyperterminal. Severity is high (CVSS 7.5). Buffer overflow in Hilgraeve, Inc. HyperTerminal client on Windows 98, ME, and 2000 allows remote attackers to execute arbitrary commands via a long telnet URL, aka the "HyperTerminal Buffer Overflow" vulnerability.
How urgent is CVE-2000-0991?
Priority 55/100. High severity; EPSS top 4%: very likely to be exploited; Public exploit reference