Analyst readout for executives and security teams
Plain-English summary
CVE-2026-12222 affects Yealink SIP-T46U phones running version 108.86.0.118. A local-network attacker with low privileges could trigger a memory corruption flaw in a web service endpoint. Public exploit material is reported, but CISA KEV is not listed and the sources do not show confirmed active exploitation.
Executive priority
Treat as a high-priority network containment and vendor-follow-up item, especially in environments with Yealink SIP-T46U phones. The main business risk is compromise or disruption of voice devices from inside the network. Immediate action should focus on inventory, segmentation, access restriction, and monitoring until vendor guidance is available.
Technical view
The issue is a stack-based buffer overflow in mod_webd.BlueToothTest within /api/inner/bttest of the Web FastCGI Service. Manipulation of btMac, pin, or reserved can impact confidentiality, integrity, and availability. CVSS 4.0 is 8.6 with adjacent-network attack vector, low complexity, low privileges, and no user interaction.
Likely exposure
Exposure appears limited to Yealink SIP-T46U devices on firmware 108.86.0.118 where the web service is reachable from the local or adjacent network. Internet exposure is not stated in the sources. Organizations with flat voice networks, shared LAN access, or weak device-management segmentation have higher practical risk.
Exploitation context
VulDB states the exploit has been publicly disclosed and may be utilized. The source bundle does not prove active exploitation, and KEV is false. The attacker needs local-network access and low privileges, reducing broad internet-scale risk but increasing concern for compromised internal networks or untrusted LAN segments.
Researcher notes
Evidence is currently third-party advisory driven. Vendor contact reportedly received no response, and no official fix is named in the provided sources. Avoid assuming broader Yealink model impact beyond SIP-T46U 108.86.0.118. Public exploit disclosure raises urgency, but active exploitation is not established.
Mitigation direction
- Check Yealink support channels for firmware or mitigation guidance.
- Apply a vendor-provided update if one becomes available.
- Restrict phone web management access to trusted admin hosts.
- Segment voice devices from user and guest networks.
- Block unnecessary access to the affected web service where feasible.
- Monitor for suspicious access to /api/inner/bttest.
Validation and detection
- Inventory Yealink SIP-T46U devices and record firmware versions.
- Prioritize devices running firmware 108.86.0.118.
- Confirm management interfaces are not reachable from untrusted LAN segments.
- Review logs for unexpected /api/inner/bttest access.
- Track CVE, VulDB, and Yealink updates for patch information.
Public sources used
Based on public source material and reviewed before publication.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-119: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-121: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-12222 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.6 (4.0)
- Known Exploited
- No
- Published
Vector: 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
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
4 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
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 — — VulDB CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R 2.1 5.9 VulDB CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R 2.1 5.9 VulDB AV:A/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:UR 5.1 10 VulDB Vulnerability scoring details
Base CVSS 4.0 score
8.6 HighVector: 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
Base CVSS 3.1 score
8 HighVector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R
Base CVSS 3.0 score
8 HighVector: CVSS:3.0/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R
Base CVSS 2.0 score
7.7 HighVector: AV:A/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:UR
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- Source timeline VulDB
Advisory disclosed
- Source timeline VulDB
VulDB entry created
- CVE reserved CVE Program
The CVE ID was reserved by the assigning CNA.
- Source timeline VulDB
VulDB entry last update
- CVE published CVE Program
The CVE record was published.
- CVE updated CVE Program
The CVE record metadata indicates this as the latest update time.
Source materials
- CVE List V5 source CVE List V5
- VDB-370865 | Yealink SIP-T46U Web FastCGI Service bttest mod_webd.BlueToothTest stack-based overflow CVE reference, VulDB · vdb-entry, technical-description
- VDB-370865 | CTI Indicators (IOB, IOC, IOA) CVE reference, VulDB · signature, permissions-required
- CVE-2026-12222 | CVE Analysis and Report CVE reference, VulDB · third-party-advisory
- Submit #834602 | yealink T46U 108.86.0.118 Stack-based Buffer Overflow CVE reference, VulDB · third-party-advisory
- http://cdn2.v50to.cc/T46U/T46U_mod_webd_BlueToothTest_off_by_one.zip CVE reference, VulDB · broken-link, exploit
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Restriction of Operations within the Bounds of a Memory Buffer
Improper Restriction of Operations within the Bounds of a Memory Buffer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Stack-based Buffer Overflow
Stack-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.