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

Published Jun 15, 2026

Updated

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 approached within the local network. The exploit has been made public and could be used. The vendor was contacted early about this disclosure and is working on a patch to fix it.

Affected Software

1 affected component

Yealink SIP-T46U=108.86.0.118

Event History

Jun 15, 2026

CVE Published

via MITRE·05:00 AM

Data Sourced

via MITRE·05:00 AM

DescriptionSeverityWeakness

Data Sourced

via NVD·06:16 AM

DescriptionSeverityWeakness

Oct 17, 58423

Event

via NVD·08:58 PM

Frequently Asked Questions

What is the severity of CVE-2026-12221?

CVE-2026-12221 has a severity rating of 8, classified as high.

How do I fix CVE-2026-12221?

To fix CVE-2026-12221, update the Yealink SIP-T46U firmware to the latest version provided by the vendor.

What type of vulnerability is CVE-2026-12221?

CVE-2026-12221 is a stack-based buffer overflow vulnerability.

What component is affected by CVE-2026-12221?

CVE-2026-12221 affects the Firmware Chunk Upload Handler in Yealink SIP-T46U.

What is the potential impact of exploiting CVE-2026-12221?

Exploitation of CVE-2026-12221 could allow an attacker to perform arbitrary code execution.