CVE-2000-0665: GAMSoft TelSrv telnet server denial of service via long username

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 20 September 2026. Confidence: medium.

medium priorityThe flaw is a remotely reachable, unauthenticated denial of service with public exploit references and high EPSS, but it only causes availability loss and is not in KEV.

What it is

GAMSoft TelSrv 1.5 and earlier fails to handle an overly long username, allowing a remote attacker to crash the telnet server. The flaw is a straightforward denial of service with no confidentiality or integrity impact, but it can take the service offline for legitimate users.

Impact

An attacker can cause the TelSrv service to become unavailable, disrupting telnet access for all users of the affected host. No data disclosure or code execution is described.

Attack surface

Reachable over the network via the telnet service; the CVSS vector (AV:N/AC:L/Au:N) indicates no authentication and no user interaction are required. The attacker only needs to supply a long username during the telnet login exchange.

Exploitation

Public exploit and vendor advisory references exist, and EPSS is high (0.5099, ~98.9th percentile), but the CVE is not listed in CISA KEV, so no confirmed in-the-wild exploitation is documented in this record.

What to do

• Upgrade TelSrv to a version later than 1.5 if the vendor provides one; the referenced advisory is tagged Patch, so apply the vendor fix first.
• If no patched version is available, restrict telnet access to trusted networks or disable the service where it is not needed.
• Place the service behind a firewall or access control list that limits who can reach the telnet port.
• Monitor the vendor and advisory references for an updated release and retire the product if it is no longer maintained.

Detection

• Monitor TelSrv process crashes or restarts and correlate them with inbound telnet connections.
• Alert on unusually long username strings in telnet authentication attempts logged by the host or network sensors.
• Watch for repeated connection attempts to the telnet port from a single source that precede a service outage.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.