CVE-2025-71056 in EPON 1GE ONU
Summary
by MITRE • 02/23/2026
Improper session management in GCOM EPON 1GE ONU version C00R371V00B01 allows attackers to execute a session hijacking attack via spoofing the IP address of an authenticated user.
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Analysis
by VulDB Data Team • 02/27/2026
The vulnerability identified as CVE-2025-71056 represents a critical session management flaw within the GCOM EPON 1GE ONU firmware version C00R371V00B01. This issue stems from inadequate session token handling and validation mechanisms that fail to properly authenticate subsequent requests from the same user. The vulnerability specifically affects the network infrastructure equipment used in passive optical network deployments where the ONU (Optical Network Unit) serves as the customer premises equipment connecting to the optical distribution network. The flaw enables attackers to exploit the system's weak session validation processes by spoofing legitimate user IP addresses, thereby gaining unauthorized access to authenticated sessions and potentially compromising the entire network segment under the control of the compromised ONU.
The technical root cause of this vulnerability lies in the improper implementation of session identification and validation protocols within the firmware's authentication framework. When legitimate users establish sessions with the ONU device, the system fails to adequately bind session tokens to specific network contexts or implement robust IP address verification mechanisms. This weakness allows an attacker positioned within the same network segment or capable of IP address spoofing to intercept valid session tokens and reuse them to impersonate authenticated users. The vulnerability operates under the broader category of improper session management as classified by CWE-613, which specifically addresses the failure to properly manage session identifiers and their associated security contexts. This weakness directly enables session hijacking attacks by allowing unauthorized entities to leverage existing authenticated sessions without proper authentication.
The operational impact of CVE-2025-71056 extends beyond simple unauthorized access to encompass potential network disruption, data compromise, and lateral movement within the affected network infrastructure. An attacker exploiting this vulnerability could gain administrative privileges to configure network parameters, modify traffic routing, or even redirect network traffic to malicious endpoints. The implications are particularly severe in enterprise and service provider environments where these ONUs form part of critical network infrastructure, as they may control access to internal networks and customer services. The vulnerability creates a persistent threat vector that could allow attackers to maintain long-term access to the network segment, enabling them to conduct reconnaissance, data exfiltration, or further compromise adjacent network systems. This risk is amplified by the fact that the attack requires minimal privileges to execute and can be performed by attackers with basic network access.
Mitigation strategies for CVE-2025-71056 should focus on strengthening session management protocols and implementing robust authentication mechanisms within the GCOM EPON 1GE ONU firmware. Network administrators should prioritize immediate firmware updates from GCOM to address the identified session management flaws, as these typically include enhanced token binding mechanisms and improved IP address validation procedures. Additional protective measures include implementing network segmentation to isolate affected ONUs from critical network segments, deploying network access control policies that restrict communication between authenticated and unauthenticated network zones, and monitoring for suspicious session activity or unusual IP address patterns. Organizations should also consider implementing multi-factor authentication mechanisms where possible and establishing regular vulnerability assessments to identify similar session management weaknesses in other network infrastructure components. The mitigation approach aligns with ATT&CK technique T1566 which covers credential harvesting and session hijacking attacks, emphasizing the need for robust session management as a primary defense mechanism.