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Memory Buffer Bounds ErrorWeakness · CWE-119

CVE-2026-12218

HIGH · 8.0 CVSS v3.1 Published 2026-06-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
82/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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 and is working on a patch to fix it.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Stack-based buffer overflow in Yealink SIP-T46U phone firmware (v108.87.50.1) Web FastCGI Service. The /api/inner/beforewifitest endpoint's StartReportInformation function fails to properly bounds-check the 'port' argument, allowing attackers with local network access to overflow the stack and potentially execute arbitrary code.

MitigationApply vendor firmware patch when released; until then, isolate affected devices on restricted VLANs and disable the web interface or limit access to trusted management subnets.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Adjacent
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the device model
    Check the device label or access the web interface and look for the model number in the system information or status page
    Affected if Device is not a Yealink SIP-T46U IP phone
  2. Determine the firmware version
    Access the web interface, navigate to Status or System Info page to view the firmware version. Compare against v108.87.50.1
    Affected if Firmware version is v108.87.50.1 or lower
  3. Verify the web interface is network accessible
    Attempt to reach the device's IP address on HTTP port 80 or HTTPS port 443 from a remote host
    Affected if Web interface responds to network requests (vulnerable service is exposed)
  4. Confirm the vulnerable endpoint exists
    Send a GET or POST request to /api/inner/beforewifitest endpoint with any 'port' parameter value and observe the response
    Affected if Endpoint responds (indicates the vulnerable WiFi testing functionality is enabled)
  5. Assess network exposure
    Determine if the device IP is reachable from untrusted network segments, VLANs, or the internet by reviewing network topology and firewall rules
    Affected if Device web interface is accessible from untrusted or external networks

You are affected if you have a Yealink SIP-T46U running firmware v108.87.50.1 or lower with the web interface accessible from a network where untrusted attackers can reach the /api/inner/beforewifitest endpoint.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor firmware patch when released; until then, isolate affected devices on restricted VLANs and disable the web interface or limit access to trusted management subnets.

Recommended fix Moderate confidence
  1. Restrict network access to the Yealink SIP‑T46U web interface by placing it behind a firewall or using ACLs to allow only trusted IP addresses, as the attack requires local network access.
  2. If the web FastCGI service is not required, disable it via the device’s management interface or firmware settings.
  3. Monitor Yealink’s official support channels (firmware release notes, security advisories) for the upcoming patch that addresses the stack‑based buffer overflow in /api/inner/beforewifitest (argument port).
  4. Once the vendor releases a firmware update that includes the fix, schedule a maintenance window, back up the device configuration, and upgrade the device to the fixed firmware version.
  5. After applying the patch, verify that the vulnerability is resolved and that the device operates normally.
Caveat Firmware updates may temporarily disrupt phone service; test the new firmware in a non‑production environment before deploying.

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-12218 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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