Authentication Bypass in Slican telephone exchanges

Summary

In Slican telephone exchanges it is possible to manage the control panel remotely. An unauthenticated attacker can connect to the modem via a telephone with a specific caller ID. This allows them to bypass admin authentication and gain full access to the service protocol and configuration panel. This vulnerability is independent of the telephone exchanges configuration. If remote access is disabled, calling with this caller ID will temporarily enable it. This issue was fixed in versions below: • IPL-256: version 6.61.0040 • IPM-032: version 6.61.0040 • CCT-1668: version 6.56.0430 • MAC-6400: version 6.56.0430 • CXS-0424: version 6.30.0510 The issue STILL EXISTS in End-Of-Life telephone exchanges in versions 4.xx and below: • CCT-1668 (CCT1CPU) • MAC-6400 • CXS-0424 These products were discontinued in 2011 and 2012 and and will not receive updates. These products require a hardware update in order to receive a software update. The vendor recommends that users of these devices contact the their service department directly to determine the options for upgrading.

Timeline

1. May 27, 2026, 12:42 PM UTCCVE published
2. May 27, 2026, 3:28 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. May 27, 2026, 3:29 PM UTCRecord last updated

Affected versions

• Slican CCT-1668

  fixed in 6.56.0430

• Slican MAC-6400

  fixed in 6.56.0430

• Slican CXS-0424

  fixed in 6.30.0510

• Slican IPL-256

  fixed in 6.61.0040

• Slican IPM-032

  fixed in 6.61.0040

References 1