CVE intelligence and bounded remediation

CVE-2018-16221 — Yealink Ultra-Elegant Ip Phone Sip-T41P Firmware security vulnerability

High CVSS 8

The diagnostics web interface in the Yeahlink Ultra-elegant IP Phone SIP-T41P (firmware 66.83.0.35) does not validate (escape) the path information (path traversal), which allows an authenticated remote attacker to get access to privileged information (e.g., /etc/passwd) via path traversal (relative path information in the file parameter of the corresponding POST request).

Severity
High
CVSS
8 (3.0)
Published
2019-05-29
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-22

Affected products

  • yealink / ultra-elegant_ip_phone_sip-t41p_firmware / 66.83.0.35

Matched remediation archetype

Path traversal, unsafe upload, and file handling

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Check exposure

  • Trace untrusted filenames, archive entries, URLs, and path segments into read, write, include, extraction, and upload operations.
  • Identify filesystem roots, mount permissions, symbolic-link behavior, archive handling, and whether uploaded content is web-accessible or executable.
  • Review canonicalization and containment checks across supported operating systems and storage backends.

Remediate safely

  • Generate server-side storage identifiers and resolve paths beneath a fixed root using filesystem-aware containment checks.
  • Reject absolute, parent-relative, alternate-separator, device, link, and archive entries that escape the intended root.
  • Store uploads outside executable or served paths, validate type and size, and use private atomic temporary files.

Authoritative sources

Complete CVE record and remediation plan

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