A critical vulnerability, tracked as CVE-2025-20309, has been discovered in Cisco Unified Communications Manager (Unified CM) and its Session Management Edition (Unified CM SME), potentially allowing unauthenticated, remote attackers to gain root access using static, hardcoded credentials.
The flaw, assigned a CVSS score of 10.0 (maximum severity), affects Engineering Special (ES) releases 15.0.1.13010-1 through 15.0.1.13017-1 and is caused by development-stage credentials inadvertently left in production code.
The vulnerability, classified under CWE-798 (Use of Hard-coded Credentials), enables attackers to log in as the root user via SSH, granting full control over the affected system.
Once exploited, attackers can execute arbitrary commands, manipulate configurations, intercept sensitive communications, or pivot deeper into enterprise networks.
Cisco confirmed that the static credentials for the root account cannot be changed or deleted, compounding the risk.
No Workarounds, Immediate Patch Required
Cisco has emphasized that no workarounds are available for this vulnerability.
The only way to secure affected systems is to upgrade to Unified CM and Unified CM SME 15SU3 (July 2025) or apply the dedicated patch file ciscocm.CSCwp27755_D0247-1.cop.sha512.
Earlier releases, such as 12.5 and 14, are not vulnerable.
Administrators are strongly urged to:
- Upgrade immediately to the fixed release or apply the patch.
- Audit access logs for unexpected root login attempts.
- Retrieve logs with the following CLI command: shell
file get activelog syslog/secure - Check for indicators of compromise (IoCs), such as successful SSH logins by the root user, which appear in
/var/log/active/syslog/secure: textApr 6 10:38:43 cucm1 authpriv 6 sshd: pam_unix(sshd:session): session opened for user root by (uid=0)A log entry like the above signals a possible exploitation attempt.
Industry Response and Broader Implications
While Cisco’s Product Security Incident Response Team (PSIRT) reports no evidence of exploitation in the wild, the presence of a hardcoded root account constitutes a significant supply-chain risk and echoes previous incidents involving backdoor credentials in other Cisco products.
Such flaws highlight ongoing challenges in secure software development lifecycles, particularly in enterprise communications platforms central to daily business operations.
Security experts recommend that organizations review their Unified CM deployments immediately, prioritize patching, and monitor for any suspicious root-level access.
For customers without service contracts, Cisco advises contacting their Technical Assistance Center (TAC) with the product serial number and the advisory URL to obtain the necessary updates.
Technical Details at a Glance
| Technical Term | Description |
|---|---|
| CVE-2025-20309 | Vulnerability identifier for the static SSH root credential flaw |
| CVSS 10.0 | Maximum severity rating, indicating critical risk |
| CWE-798 | Secure Shell protocol is used for remote system access |
| CSCwp27755 | Cisco Bug ID for tracking the issue |
| SSH | Secure Shell protocol used for remote system access |
| IoC | Indicator of Compromise, such as a root SSH login event |
Organizations are advised to act swiftly, as the window for exploitation remains open until all vulnerable systems are patched.
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