CVE-2026-109506 in RE190
Summary
by MITRE • 10/15/2026
Multiple TP-Link Wi-Fi range extenders use a custom, reversible XOR-and-dictionary transformation in the HTTP web-management login flow. An unauthenticated attacker on the same local network who can capture the network traffic associated with legitimate administrator login may be able to derive an alternative credential value that produces the same accepted authentication result and use it to authenticate to the device’s web-management interface with administrator privileges. Exploitation requires the management login to use HTTP and the attacker to observe the session key, dictionary, and login value associated with a legitimate administrator login.
Successful exploitation may allow an unauthenticated adjacent attacker to gain administrator access to the affected device and modify exposed configuration settings.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability affects multiple TP-Link Wi-Fi range extenders that employ a custom authentication mechanism within their HTTP web-management interface. This specific implementation utilizes a reversible transformation process based on XOR operations combined with dictionary lookups during the login sequence. The core technical flaw lies in the cryptographic weakness of this scheme, which fails to provide adequate confidentiality or integrity for administrative credentials transmitted over unencrypted channels. Because the transformation is deterministic and reversible given sufficient context, it does not rely on strong asymmetric cryptography or secure key exchange protocols that would prevent offline analysis by an adversary. Instead, the system relies on obscurity and a static dictionary structure that can be reverse-engineered if the internal state of the authentication process is observed.
Exploitation requires an attacker to be positioned as an adjacent node on the same local network segment where the vulnerable device resides. The primary prerequisite for this attack is the ability to capture network traffic associated with a legitimate administrator login attempt. By monitoring the HTTP requests and responses, the attacker can extract three critical components: the session key used during the exchange, the dictionary or lookup table employed by the firmware, and the specific login value transmitted from the client. With these elements in hand, an adversary can perform offline analysis to derive alternative credential values that produce the same authentication result as the original legitimate credentials. This effectively allows for a collision attack where different input strings yield identical accepted authentication tokens, bypassing the need to know the actual password.
The operational impact of this vulnerability is severe, granting unauthenticated adjacent attackers full administrator access to the affected device once they successfully authenticate using the derived credential values. Upon gaining administrative privileges, an attacker can modify exposed configuration settings, potentially altering network routing tables, disabling security features such as firewalls or WPA encryption, and injecting malicious DNS configurations to facilitate further attacks on other devices within the local network. This level of control compromises not only the integrity of the range extender itself but also serves as a pivot point for broader lateral movement across the internal infrastructure. The use of HTTP rather than HTTPS exacerbates this risk by ensuring that all authentication data, including session keys and credentials, is transmitted in cleartext, making interception trivial for any device with promiscuous mode capabilities on the local area network.
To mitigate this vulnerability, users should prioritize upgrading to firmware versions where TP-Link has addressed these cryptographic weaknesses or replaced the custom XOR-and-dictionary scheme with a standardized, secure authentication protocol such as OAuth2 or at minimum HTTPS-based basic authentication with strong hashing algorithms like bcrypt or Argon2. Network administrators must enforce the use of encrypted management interfaces and disable HTTP access if possible to prevent traffic interception. Additionally, implementing network segmentation can limit an attacker's ability to perform adjacent side-channel attacks by isolating IoT devices from critical internal networks. Regular monitoring for unusual administrative login attempts and enforcing complex password policies may also reduce the likelihood of successful credential derivation, although the fundamental flaw in the authentication logic remains the primary vector that must be addressed through software updates or hardware replacement if patches are unavailable. This vulnerability aligns with CWE-287 Improper Authentication due to weak cryptographic implementation and maps to MITRE ATT&CK techniques related to Credential Access via Network Sniffing and Initial Access from Local Networks, highlighting the critical need for robust authentication mechanisms in embedded IoT devices.