CVE-2026-12221 Yealink SIP-T46U Firmware Chunk Upload upgrade sprintf stack-based overflow

A vulnerability was found in Yealink SIP-T46U 108.86.0.118. This impacts the function sprintf of the file /api/upgrade/upgrade of the component Firmware Chunk Upload Handler. Performing a manipulation of the argument uid/startoffset results in stack-based buffer overflow. The attack needs to be...