CVE-1999-1559: Xylan OmniSwitch before 3.2.6 allows remote attackers to bypass the login prompt via a CTRL-D (control d) c...

Security readout for executives and security teams

This is an old network switch login bypass affecting Xylan OmniSwitch software before 3.2.6. A remote party could bypass the login prompt using a specific control character and then prevent other users from accessing the switch because only one session is supported. Exposure is most likely in legacy environments still operating Xylan OmniSwitch devices with software earlier than 3.2.6, especially where management access is reachable beyond trusted administration networks. Treat this as a legacy infrastructure risk, not a current mass-exploitation emergency based on the supplied evidence. Prioritize confirmation if old Xylan OmniSwitch devices remain in production or management interfaces are broadly reachable. Mitigation focus: Identify any Xylan OmniSwitch devices still in service.; Verify switch software version against the pre-3.2.6 affected range.; Upgrade to version 3.2.6 or later if vendor guidance supports it..

Prepared

Jul 1, 2026, 08:44 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.