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CVE Record

CVE-2018-16221: The diagnostics web interface in the Yeahlink Ultra-elegant IP Phone SIP-T41P (firmware 66.83.0.35) does no...

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).

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2018-16221 is an authenticated information-disclosure flaw in the diagnostics web interface of the Yealink/Yeahlink Ultra-elegant IP Phone SIP-T41P firmware 66.83.0.35. A logged-in remote attacker could abuse path traversal handling to read privileged files. The sources do not provide CVSS, public exploitation evidence, or a named vendor fix.

Executive priority

Treat this as a targeted telecom device hardening issue. Prioritize exposed or broadly accessible phone administration interfaces, especially in offices using the named model and firmware.

Technical view

The diagnostics web interface fails to validate or escape path information. The CVE describes relative path traversal in a file parameter of a POST request, allowing authenticated remote access to privileged information such as system account files. Evidence is limited to the CVE record and Fraunhofer advisory reference.

Likely exposure

Exposure is most likely where SIP-T41P phones with firmware 66.83.0.35 have reachable web administration or diagnostics interfaces and weakly controlled authenticated access.

Exploitation context

The vulnerability requires authentication according to the CVE description. It is not listed in CISA KEV in the supplied bundle, and no cited source here confirms active exploitation.

Researcher notes

The source data names a specific model and firmware but lacks CPEs, CVSS, CWE mapping, and remediation detail. Keep findings scoped to authenticated path traversal and privileged file disclosure until vendor guidance confirms broader impact.

Mitigation direction

  • Inventory Yealink/Yeahlink SIP-T41P devices and firmware versions.
  • Restrict web management and diagnostics interfaces to trusted administration networks.
  • Review vendor or Fraunhofer guidance for firmware updates or workarounds.
  • Disable unnecessary diagnostics or web administration access where operationally feasible.
  • Enforce strong credentials and remove shared or default administrative accounts.

Validation and detection

  • Confirm whether any SIP-T41P devices run firmware 66.83.0.35.
  • Verify management interfaces are not exposed to untrusted networks.
  • Review access logs for unusual authenticated diagnostics activity.
  • Check configuration standards for credential hygiene and administrative network restrictions.
Prepared
Confidence
medium
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

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.

description · low confidence lookup

File access behavior lookup

The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2018-16221 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 profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

0CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

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