CVE-2026-12221 HIGH

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

Vendor Yealink
Product SIP-T46U
Weakness CWE-121
Published June 15, 2026
Last update June 15, 2026

CVSS base score

8.6/10
Attack vector Adjacent
Attack complexity Low
Privileges required Low
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P

What the vulnerability does

01Description

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/start_offset results in stack-based buffer overflow. The attack needs to be approached within the local network. The exploit has been made public and could be used. The vendor was contacted early about this disclosure but did not respond in any way.

Key dates

02Disclosure timeline

June 15, 2026 CVE published
June 15, 2026 Record updated