Gregory Duchemin

The issue allows remote authenticated users to gain privileges. This is achieved by setting the `admin` parameter to a specific `$admin` value in an edit action to the `/admin/user/user.cgi` API endpoint and possibly other components.

The issue is caused by an integer signedness error that allows remote attackers to cause a denial of service, specifically IP lease depletion, via a DHCP request. This request has the LEASETIME option set to -1, making the DHCP lease valid for thirteen or more years.

A cross-site scripting (XSS) issue allows remote attackers to execute arbitrary scripts as other users. This is achieved via the `CLIENTID` or `HOSTNAME` option of a DHCP request.

The issue is related to a buffer overflow in the logging capability for the DHCP daemon. This can be triggered by remote attackers sending multiple hostname options in various DHCP messages, such as DISCOVER, OFFER, REQUEST, ACK, or NAK messages. The vulnerability can cause a denial of service, resulting in a server crash, and potentially allow the execution of arbitrary code when a long string is generated while writing to a log file.

The issue arises when the DHCP daemon (DHCPD) for ISC DHCP is compiled in environments lacking the vsnprintf function, leading to the use of C include files that define vsnprintf to use the less safe vsprintf function. This can result in buffer overflow vulnerabilities, enabling a denial of service (server crash) and possibly allowing the execution of arbitrary code.