CVE-2025-11534: Raisecom SSH Auth Bypass Vulnerability

CVE-2025-11534 Overview

CVE-2025-11534 is a critical authentication bypass vulnerability affecting Raisecom network devices. The flaw allows SSH sessions to be established without completing user authentication, enabling attackers to gain shell access to affected devices without valid credentials. This vulnerability represents a severe security risk for organizations using affected Raisecom equipment, as it provides a direct path to unauthorized system access via the network.

Critical Impact

Attackers can establish SSH sessions and gain shell access to Raisecom devices without providing valid credentials, potentially leading to full system compromise, unauthorized configuration changes, and use of the device as a pivot point for further network attacks.

Affected Products

• Raisecom network devices with SSH enabled
• Specific affected firmware versions detailed in CISA ICS Advisory ICSA-25-294-06

Discovery Timeline

• 2025-10-21 - CVE-2025-11534 published to NVD
• 2025-10-21 - Last updated in NVD database

Technical Details for CVE-2025-11534

Vulnerability Analysis

This vulnerability is classified as CWE-288 (Authentication Bypass Using an Alternate Path or Channel). The affected Raisecom devices contain a flaw in their SSH implementation that permits attackers to bypass the standard authentication flow entirely. Rather than requiring valid username and password credentials to establish a session, the vulnerable SSH service allows connections to proceed to an authenticated shell state without proper credential verification.

The network-accessible nature of this vulnerability significantly increases its risk profile. Any attacker who can reach the SSH service on an affected Raisecom device can potentially exploit this flaw to gain unauthorized access. The impact includes complete compromise of confidentiality, integrity, and availability of the affected device.

Root Cause

The root cause of CVE-2025-11534 lies in improper authentication handling within the SSH service implementation on affected Raisecom devices. The authentication mechanism fails to properly validate that a user has successfully completed the credential verification process before granting shell access. This allows an attacker to use an alternate authentication path that bypasses the intended security controls.

Attack Vector

The attack vector for CVE-2025-11534 is network-based. An unauthenticated remote attacker can exploit this vulnerability by initiating an SSH connection to the target device and manipulating the authentication sequence to bypass credential verification. No user interaction is required, and the attack can be executed without any prior privileges on the target system.

The exploitation mechanism involves establishing an SSH connection to the vulnerable device and leveraging the authentication bypass to gain shell access. For detailed technical information about the exploitation technique, refer to the RunZero Advisory for CVE-2025-11534.

Detection Methods for CVE-2025-11534

Indicators of Compromise

• Unexpected SSH sessions established from unknown or untrusted IP addresses
• SSH connection logs showing successful authentication without corresponding authentication attempts
• Unusual command execution or configuration changes on Raisecom devices
• Network traffic patterns indicating automated scanning or exploitation attempts against SSH services

Detection Strategies

• Monitor SSH authentication logs for sessions that bypass normal authentication sequences
• Implement network intrusion detection rules to identify SSH connection anomalies targeting Raisecom devices
• Deploy asset discovery tools to identify all Raisecom devices in your environment and their SSH exposure
• Use network traffic analysis to detect suspicious SSH session establishment patterns

Monitoring Recommendations

• Enable verbose logging on Raisecom devices to capture detailed SSH session information
• Configure SIEM alerts for SSH authentication anomalies on network infrastructure devices
• Implement continuous network monitoring to detect unauthorized access attempts to management interfaces
• Review SSH session logs regularly for signs of unauthorized access or exploitation attempts

How to Mitigate CVE-2025-11534

Immediate Actions Required

• Restrict SSH access to Raisecom devices to trusted management networks only using firewall rules or ACLs
• Disable SSH on affected devices if not required for operational purposes
• Implement network segmentation to isolate affected devices from untrusted networks
• Monitor all access to affected devices for signs of exploitation until patches can be applied

Patch Information

Refer to the CISA ICS Advisory ICSA-25-294-06 for official patch information and vendor guidance. Contact Raisecom support for specific firmware updates addressing this vulnerability. Organizations should prioritize applying patches to devices exposed to untrusted networks or the internet.

Workarounds

• Implement strict network access controls to limit SSH connectivity to authorized management stations only
• Use a VPN or jump host to access Raisecom device management interfaces rather than direct SSH exposure
• Consider disabling SSH entirely and using alternative management methods such as console access until patches are available
• Deploy network-based intrusion prevention systems to detect and block exploitation attempts

# Example ACL configuration to restrict SSH access
# Limit SSH access to trusted management subnet only
# Apply on device or upstream firewall

# Allow SSH from management network
permit tcp 10.10.10.0/24 any eq 22

# Deny all other SSH access
deny tcp any any eq 22