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Description

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.

PUBLISHED Reserved 2026-06-14 | Published 2026-06-15 | Updated 2026-06-15 | Assigner VulDB




HIGH: 8.6CVSS: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
HIGH: 8.0CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R
HIGH: 8.0CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R
7.7AV:A/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:UR

Problem types

Stack-based Buffer Overflow

Memory Corruption

Product status

108.86.0.118
affected

Timeline

2026-06-14:Advisory disclosed
2026-06-14:VulDB entry created
2026-06-14:VulDB entry last update

Credits

CookedMelon (VulDB User) reporter

VulDB CNA Team coordinator

References

vuldb.com/vuln/370864 (VDB-370864 | Yealink SIP-T46U Firmware Chunk Upload upgrade sprintf stack-based overflow) vdb-entry technical-description

vuldb.com/vuln/370864/cti (VDB-370864 | CTI Indicators (IOB, IOC, IOA)) signature permissions-required

vuldb.com/cve/CVE-2026-12221 (CVE-2026-12221 | CVE Analysis and Report) third-party-advisory

vuldb.com/submit/834207 (Submit #834207 | yealink T46U 108.86.0.118 Stack-based Buffer Overflow) third-party-advisory

cdn2.v50to.cc/...od_upgrade_Upgrade_chunk_stack_overflow.zip broken-link exploit patch

cve.org (CVE-2026-12221)

nvd.nist.gov (CVE-2026-12221)

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