840g Firmware CVE-2025-7571

This vulnerability presents a HIGH real-world risk despite the authentication requirement. CVSS 3.1 score of 8.8 reflects High severity: network-accessible (AV:N), low complexity (AC:L), but requires low privilege (PR:L) authentication. The presence of a public proof-of-concept significantly elevates exploitation likelihood. The lack of vendor response and absence of patched versions means no remediation path exists for deployed devices. EPSS score (if available) would likely be elevated due to POC availability. Under SSVC framework: exploitation is disclosed/public (Proof of Concept), the attack is automatable (buffer overflow triggered via HTTP request), and technical impact is complete (arbitrary code execution). The authentication requirement (PR:L) is a mitigating factor but not negligible—many deployments have weak or default credentials. This is a HIGH priority for organizations running affected UTT HiPER 840G devices, particularly in perimeter or guest network deployments where authenticated access may be easier to obtain.

An attacker with network access to an organization's administrative LAN obtains valid credentials (through phishing, credential reuse, or default credentials) for the UTT HiPER 840G access point. The attacker crafts an HTTP POST request to http://[device-ip]/goform/aspApBasicConfigUrcp with a maliciously long Username parameter (e.g., 1000+ bytes of crafted data containing shellcode and return address overwrite). The vulnerable endpoint processes the oversized input without bounds checking, corrupting the stack. The attacker's payload overwrites the return address of the configuration function, redirecting execution to injected shellcode. The attacker achieves remote code execution with the privileges of the web server process (typically root on embedded devices), gaining full device control to intercept traffic, modify configuration, or use the device as a pivot point into the internal network. Public POC availability means this attack requires minimal sophistication to execute.