Buffer overflow in Yealink Sip-T46u
CVE-2026-12221
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.0 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (28.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 28.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Yealink Sip-T46u — versions 108.86.0.118
Weakness classification (CWE)
References
- cdn2.v50to.cc/T46U/T46U_mod_upgrade_Upgrade_chunk_stack_overflow.zip (exploit, patch, broken-link)
- vuldb.com/cve/CVE-2026-12221 (third-party-advisory)
- vuldb.com/submit/834207 (third-party-advisory)
- vuldb.com/vuln/370864 (technical-description, vdb-entry)
- vuldb.com/vuln/370864/cti (signature, permissions-required)
Frequently asked questions
- What is CVE-2026-12221?
- CVE-2026-12221 is a high-severity vulnerability in Yealink Sip-T46u, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 8.0/10. Published 2026-06-15.
- How severe is CVE-2026-12221?
- High severity. CVSS v3 base score is 8.0 out of 10.