CVE-2026-27755: Sodola SL902 Auth Bypass Vulnerability

CVE-2026-27755 Overview

CVE-2026-27755 is a critical weak session identifier generation vulnerability affecting SODOLA SL902-SWTGW124AS network switch firmware. The vulnerability exists in firmware versions through 200.1.20 and allows attackers to forge authenticated sessions by computing predictable MD5-based cookies. Attackers who know or guess valid credentials can calculate the session identifier offline and bypass authentication without completing the login flow, gaining unauthorized access to the device.

This vulnerability is classified under CWE-330 (Use of Insufficiently Random Values), indicating that the session generation mechanism uses predictable values that can be computed or guessed by an attacker.

Critical Impact

Remote attackers can bypass authentication entirely by forging predictable session identifiers, enabling complete unauthorized control of the affected network switch without valid credentials.

Affected Products

• SODOLA SL902-SWTGW124AS Firmware versions through 200.1.20
• SODOLA SL902-SWTGW124AS Hardware Device

Discovery Timeline

• 2026-02-27 - CVE-2026-27755 published to NVD
• 2026-03-03 - Last updated in NVD database

Technical Details for CVE-2026-27755

Vulnerability Analysis

The SODOLA SL902-SWTGW124AS network switch contains a fundamental flaw in its session management implementation. Rather than using cryptographically secure random number generation for session identifiers, the firmware relies on MD5 hashing of predictable inputs to generate authentication cookies. This design allows attackers to precompute or derive valid session tokens without interacting with the authentication mechanism.

The network-accessible nature of the vulnerability means any attacker with network access to the management interface can attempt exploitation. The attack requires no user interaction and can be executed with no prior authentication, making it particularly dangerous for internet-exposed devices or those accessible from untrusted network segments.

Successful exploitation grants the attacker full authenticated access to the device, enabling configuration changes, traffic interception capabilities, and potential lateral movement within the network infrastructure.

Root Cause

The root cause is the use of insufficiently random values (CWE-330) in the session identifier generation process. The firmware generates session cookies using MD5 hashing of predictable components, likely including user credentials or other static/semi-static values. MD5's deterministic nature means that identical inputs always produce identical outputs, allowing attackers who can determine or guess the input values to compute valid session identifiers offline.

Proper session management requires cryptographically secure pseudo-random number generators (CSPRNGs) to ensure session identifiers are computationally infeasible to predict or forge.

Attack Vector

The attack vector is network-based and exploits the predictable session generation mechanism in the device's web management interface. An attacker with knowledge of valid credentials (obtained through default credentials, credential stuffing, or other means) can:

1. Determine the predictable components used in session ID generation
2. Compute the MD5 hash that constitutes the session cookie offline
3. Inject the forged session cookie into HTTP requests
4. Gain authenticated access without completing the standard login flow

This bypass of the authentication flow may evade logging mechanisms that track login attempts, making the attack more difficult to detect through traditional authentication monitoring.

Detection Methods for CVE-2026-27755

Indicators of Compromise

• Authenticated management sessions appearing without corresponding login events in device logs
• Session cookies that correlate with known MD5 hashes of credential combinations
• Management interface access from unexpected source IP addresses or geographic locations
• Configuration changes with no associated successful authentication records

Detection Strategies

• Monitor for HTTP requests to the management interface containing session cookies without preceding authentication requests
• Implement network intrusion detection rules to flag direct management interface access bypassing login endpoints
• Deploy web application firewall rules to detect session cookie injection patterns
• Correlate management interface access logs with authentication logs to identify discrepancies

Monitoring Recommendations

• Enable comprehensive logging on network segments containing affected devices
• Configure SIEM rules to alert on management interface access without authentication events
• Monitor for bulk connection attempts to management interfaces which may indicate exploitation attempts
• Implement network segmentation monitoring to detect unauthorized access to management VLANs

How to Mitigate CVE-2026-27755

Immediate Actions Required

• Restrict network access to the device management interface using firewall rules or VLAN segmentation
• Change default credentials immediately if still in use on affected devices
• Place affected devices behind VPN or jump host requiring separate authentication
• Monitor affected devices for unauthorized configuration changes
• Consider disabling web management interface if not operationally required

Patch Information

At the time of publication, no vendor patch information is available. Organizations should monitor the Sodola Network Product Page and the VulnCheck Security Advisory for firmware updates addressing this vulnerability.

Workarounds

• Implement strict network segmentation to isolate device management interfaces from untrusted networks
• Deploy a network-based access control solution to restrict management interface access to authorized administrator workstations only
• Use SSH-based management if available as an alternative to the vulnerable web interface
• Implement additional authentication layer via VPN before management interface access
• Monitor and alert on any management interface access attempts as a compensating control

# Example firewall rule to restrict management interface access
# Adjust interface names and IP ranges for your environment
iptables -A INPUT -p tcp --dport 80 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP