Yealink SIP-T46U 108.86.0.118 Firmware Chunk Upload /api/upgrade/upgrade sprintf uid/start_offset stack-based overflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.3$0-$5k2.42

Summaryinfo

A vulnerability was found in Yealink SIP-T46U 108.86.0.118 and classified as critical. Affected is the function sprintf of the file /api/upgrade/upgrade of the component Firmware Chunk Upload Handler. Executing a manipulation of the argument uid/start_offset can lead to stack-based overflow. The identification of this vulnerability is CVE-2026-12221. The attack needs to be done within the local network. Furthermore, there is an exploit available. The vendor was contacted early about this disclosure but did not respond in any way.

Detailsinfo

A vulnerability classified as critical was found in Yealink SIP-T46U 108.86.0.118. This vulnerability affects the function sprintf of the file /api/upgrade/upgrade of the component Firmware Chunk Upload Handler. The manipulation of the argument uid/start_offset with an unknown input leads to a stack-based overflow vulnerability. The CWE definition for the vulnerability is CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). As an impact it is known to affect confidentiality, integrity, and availability.

The advisory is shared for download at cdn2.v50to.cc. This vulnerability was named CVE-2026-12221. The exploitation appears to be easy. The attack needs to be initiated within the local network. Technical details and also a public exploit are known.

It is possible to download the exploit at cdn2.v50to.cc. It is declared as proof-of-concept. The vendor was contacted early about this disclosure but did not respond in any way.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.3

VulDB Base Score: 8.0
VulDB Temp Score: 7.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Stack-based overflow
CWE: CWE-121 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Access: Public
Status: Proof-of-Concept
Download: 🔒
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

06/14/2026 Advisory disclosed
06/14/2026 +0 days VulDB entry created
06/14/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: cdn2.v50to.cc
Status: Not defined

CVE: CVE-2026-12221 (🔒)
GCVE (CVE): GCVE-0-2026-12221
GCVE (VulDB): GCVE-100-370864
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 06/14/2026 15:59
Changes: 06/14/2026 15:59 (59)
Complete: 🔍
Submitter: CookedMelon
Cache ID: 216::103

Submitinfo

Accepted

  • Submit #834207: yealink T46U 108.86.0.118 Stack-based Buffer Overflow (by CookedMelon)

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