CVE-2020-27121

A vulnerability in Cisco Unified Communications Manager IM & Presence Service (Unified CM IM&P) Software could allow an authenticated, remote attacker to cause the Cisco XCP Authentication Service on an affected device to restart, resulting in a denial of service (DoS) condition. The vulnerability is due to improper handling of login requests. An attacker could exploit this vulnerability by sending a crafted client login request to an affected device. A successful exploit could allow the attacker to cause a process to crash, resulting in a DoS condition for new login attempts. Users who are authenticated at the time of the attack would not be affected. There are workarounds that address this vulnerability.

• CWE-248
• CWE-755

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-imp-dos-uTx2dqu2Vendor Advisory
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-imp-dos-uTx2dqu2Vendor Advisory

Published

Nov 6, 2020

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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