CVE-2026-12221
Yealink SIP-T46U Firmware Chunk Upload upgrade sprintf stack-based overflow
- Published
- Updated
- Reserved
- Assigned by
- VulDB
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 and is working on a patch to fix it.
Public exploit
A reference of the record is tagged as an exploit or proof of concept: anyone can try it against an unpatched system.
Timeline
ID reserved
By VulDB
- 1 day later
· 1 day later
Published
- 12 days later
· 12 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| VulDBCNA (assigner) | 4.0 | High8.6 | 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 |
| VulDBCNA (assigner) | 3.1 | High8.0 | CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C |
| VulDBCNA (assigner) | 3.0 | High8.0 | CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:C |
| VulDBCNA (assigner) | 2.0 | High7.7 | AV:A/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:C |
| NVDNVD · Deferred | 4.0 | High7.3 | 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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.37% · top 69% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.6.
Weakness
Affected products
References (5)
- VDB-370864 | Yealink SIP-T46U Firmware Chunk Upload upgrade sprintf stack-based overflow (opens in a new tab)vdb-entrytechnical-description
- VDB-370864 | CTI Indicators (IOB, IOC, IOA) (opens in a new tab)signaturepermissions-required
- CVE-2026-12221 | CVE Analysis and Report (opens in a new tab)third-party-advisory
- Submit #834207 | yealink T46U 108.86.0.118 Stack-based Buffer Overflow (opens in a new tab)third-party-advisory
- http://cdn2.v50to.cc/T46U/T46U_mod_upgrade_Upgrade_chunk_stack_overflow.zip (opens in a new tab)broken-linkexploitpatch
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-12221)Record last updated .