CVE-2026-12221Public exploit

Authenticated device compromise via firmware chunk overflow

Published Jun 15, 2026 · Updated Jun 15, 2026

Stack-based buffer overflow in Yealink SIP-T46U 108.86.0.118 allows remote authenticated users to compromise the phone over a local network. The firmware chunk upload handler at /api/upgrade/upgrade passes attacker-controlled uid and start_offset values to sprintf without enforcing the destination stack buffer's bounds. Access requires low privileges and adjacent-network reachability; successful exploitation can corrupt memory and produce complete device compromise.

CVSS severity8.0
High
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Yealink SIP-T46U 108.86.0.118 allows remote authenticated users to compromise the phone over a local network. The firmware chunk upload handler at /api/upgrade/upgrade passes attacker-controlled uid and start_offset values to sprintf without enforcing the destination stack buffer's bounds. Access requires low privileges and adjacent-network reachability; successful exploitation can corrupt memory and produce complete device compromise.

The record

CVE
CVE-2026-12221
Published
Jun 15, 2026
Updated
Jun 15, 2026
Vendor
Yealink
Product
SIP-T46U
Classifications
CWE-121, CWE-119, T1190
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=108.86.0.118

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

Yealink · SIP-T46Uversion=108.86.0.118

Published CVSS scores

7.3VulDBCVSS: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
7.7VulDBAV:A/AC:L/Au:S/C:C/I:C/A:C
8.0VulDBCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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