Nr256Cn
Monthly
An unauthenticated stack-based buffer overflow in the Boa web server embedded in Netcore NR256CN firmware through 1.5.140116 lets remote attackers crash the router's main Boa process - and potentially execute code - by sending an HTTP Basic-auth username longer than 63 bytes to any password-protected /router/*.cgi route. The defect lives in the pre-authentication user_ok() handler, where Basic-auth usernames are copied with unbounded strcpy() into a fixed 64-byte stack buffer, so exploitation requires no credentials and no user interaction; the practical risk is governed almost entirely by exposure, since the attacker must be able to reach the device's HTTP management interface (far more dangerous when it faces the WAN, far less so when confined to the LAN). Per available data there is no confirmed active exploitation in CISA KEV and no public exploit code identified at time of analysis, but the zero-prerequisite access path and the network-facing attack vector make this a high-priority issue for any NR256CN with an internet-reachable admin UI.
Unauthenticated attackers with network reachability to the Boa-based web management interface of a Netcore NR256CN router (firmware through 1.5.140116) can crash the device's main Boa process by sending a Basic Authorization header whose base64-decoded value contains no colon separator - for example a value that decodes to a single character - to an auth-protected CGI route such as /router/get_user_type.cgi. The outcome is a denial of service that terminates the management interface until the web server process is restarted; per the assessed vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) there is no confidentiality or integrity impact and no code execution, and real-world risk is bounded by whether the management interface is reachable outside the LAN. No vendor patch is identified in the available data and no public exploit code is confirmed at time of analysis, though the trigger itself is trivially crafted once the interface is reachable.
Unauthenticated attackers who can reach the management interface of a Netcore NR256CN router can bypass authentication and invoke protected management CGI handlers simply by prefixing the request URI with a recognized public route such as l7_web_auth.cgi or an .ico path. The defect affects NR256CN firmware through 1.5.140116 and is rated medium severity (CVSS 4.0 base 6.9; independent assessment CVSS 3.1 6.9, AV:N/AC:L/PR:N/UI:N), with limited confidentiality and integrity impact on router management functions and no availability impact. No public exploit code identified at time of analysis, but exploitation is a single crafted HTTP request with no credentials or user interaction required, so the practical limiting factor is whether the management interface is reachable from an untrusted network rather than any exploitation complexity.
An unauthenticated stack-based buffer overflow in the Boa web server embedded in Netcore NR256CN firmware through 1.5.140116 lets remote attackers crash the router's main Boa process - and potentially execute code - by sending an HTTP Basic-auth username longer than 63 bytes to any password-protected /router/*.cgi route. The defect lives in the pre-authentication user_ok() handler, where Basic-auth usernames are copied with unbounded strcpy() into a fixed 64-byte stack buffer, so exploitation requires no credentials and no user interaction; the practical risk is governed almost entirely by exposure, since the attacker must be able to reach the device's HTTP management interface (far more dangerous when it faces the WAN, far less so when confined to the LAN). Per available data there is no confirmed active exploitation in CISA KEV and no public exploit code identified at time of analysis, but the zero-prerequisite access path and the network-facing attack vector make this a high-priority issue for any NR256CN with an internet-reachable admin UI.
Unauthenticated attackers with network reachability to the Boa-based web management interface of a Netcore NR256CN router (firmware through 1.5.140116) can crash the device's main Boa process by sending a Basic Authorization header whose base64-decoded value contains no colon separator - for example a value that decodes to a single character - to an auth-protected CGI route such as /router/get_user_type.cgi. The outcome is a denial of service that terminates the management interface until the web server process is restarted; per the assessed vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) there is no confidentiality or integrity impact and no code execution, and real-world risk is bounded by whether the management interface is reachable outside the LAN. No vendor patch is identified in the available data and no public exploit code is confirmed at time of analysis, though the trigger itself is trivially crafted once the interface is reachable.
Unauthenticated attackers who can reach the management interface of a Netcore NR256CN router can bypass authentication and invoke protected management CGI handlers simply by prefixing the request URI with a recognized public route such as l7_web_auth.cgi or an .ico path. The defect affects NR256CN firmware through 1.5.140116 and is rated medium severity (CVSS 4.0 base 6.9; independent assessment CVSS 3.1 6.9, AV:N/AC:L/PR:N/UI:N), with limited confidentiality and integrity impact on router management functions and no availability impact. No public exploit code identified at time of analysis, but exploitation is a single crafted HTTP request with no credentials or user interaction required, so the practical limiting factor is whether the management interface is reachable from an untrusted network rather than any exploitation complexity.