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CVE Record

CVE-2026-12218: Yealink SIP-T46U Web FastCGI Service beforewifitest StartReportInformation stack-based overflow

A vulnerability was detected in Yealink SIP-T46U 108.87.50.1. The affected element is the function StartReportInformation of the file /api/inner/beforewifitest of the component Web FastCGI Service. The manipulation of the argument port results in stack-based buffer overflow. Access to the local network is required for this attack. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

HighCVSS 8.6Not KEV-listed Updated
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Glexia's Take high

Analyst readout for executives and security teams

Plain-English summary

CVE-2026-12218 affects Yealink SIP-T46U phones running version 108.87.50.1. A local-network attacker with low privileges could trigger a stack buffer overflow in the phone’s web FastCGI service. Public exploit information is reported, but CISA KEV does not list active exploitation in the provided sources.

Executive priority

Treat as high priority for environments using Yealink SIP-T46U phones, especially where phone management interfaces are broadly reachable. Prioritize inventory, segmentation, and vendor guidance checks. Public exploit availability increases urgency, even without confirmed active exploitation.

Technical view

The issue is in StartReportInformation within /api/inner/beforewifitest of the Web FastCGI Service. Manipulating the port argument can cause a stack-based buffer overflow. VulDB rates it CVSS 4.0 8.6 high, with adjacent-network access, low attack complexity, low privileges, and no user interaction.

Likely exposure

Exposure is most likely where Yealink SIP-T46U phones on firmware 108.87.50.1 are reachable from user, voice, or management LANs. Internet exposure is not indicated; the source says local network access is required.

Exploitation context

The source states the exploit is public and may be used. However, the provided sources do not show confirmed active exploitation, and the CVE is not marked KEV. Attackers would need local network reachability and low privileges.

Researcher notes

Evidence is primarily from VulDB and CVE records. The vendor reportedly did not respond, and no vendor patch is named in the provided sources. Avoid assuming broader Yealink product impact beyond SIP-T46U version 108.87.50.1.

Mitigation direction

  • Inventory Yealink SIP-T46U devices and identify firmware version 108.87.50.1.
  • Restrict phone web management access to trusted administration networks only.
  • Segment voice devices from general user networks where feasible.
  • Monitor Yealink advisories for firmware updates or vendor guidance.
  • If no fix is available, reduce local network exposure and administrative access.

Validation and detection

  • Check asset inventory for Yealink SIP-T46U devices.
  • Verify firmware version on each identified device.
  • Confirm web management interfaces are not reachable from untrusted LAN segments.
  • Review access controls for low-privileged accounts on phone management services.
  • Monitor logs for unusual requests to /api/inner/beforewifitest.
Prepared
Confidence
medium
Sources
6

Public sources used

Based on public source material and reviewed before publication.

Potential ATT&CK relevance

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 · low confidence lookup

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.

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cwe · low confidence lookup

CWE-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.

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cve · low confidence lookup

CVE-2026-12218 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profile CVE Program record
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

Official CVE source material

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.

4 CVSS vectors
6 Timeline events
0 ADP providers
6 Source links

CVSS vector scores

4 official scores

We 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.

Score Version Severity Vector Exploit Impact Source
8.6 CVSS 4.0 High 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
8 CVSS 3.1 High 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
8 CVSS 3.0 High 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
7.7 CVSS 2.0 High 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 High
CVSS 4.0 vector shape for CVE-2026-12218 Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. Source timeline VulDB

    Advisory disclosed

  2. Source timeline VulDB

    VulDB entry created

  3. CVE reserved CVE Program

    The CVE ID was reserved by the assigning CNA.

  4. Source timeline VulDB

    VulDB entry last update

  5. CVE published CVE Program

    The CVE record was published.

  6. CVE updated CVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

Vendor Product Version / package Status
Yealink SIP-T46U 108.87.50.1 Listed
Weakness

CWE details

CWE-119CWE-121

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-119 · source CWE mapping

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.

Open CWE intelligence Same-CWE CVEs
CWE-121 · source CWE mapping

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.

Open CWE intelligence Same-CWE CVEs