Yealink T21P_E2 Phone 52.84.0.15 Diagnostic path traversal

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.3$0-$5k0.00

Summaryinfo

A vulnerability has been found in Yealink T21P_E2 Phone 52.84.0.15 and classified as critical. This affects an unknown function of the component Diagnostic. This manipulation causes path traversal. This vulnerability is tracked as CVE-2025-66737. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability has been found in Yealink T21P_E2 Phone 52.84.0.15 and classified as critical. Affected by this vulnerability is an unknown part of the component Diagnostic. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Yealink T21P_E2 Phone 52.84.0.15 is vulnerable to Directory Traversal. A remote normal privileged attacker can read arbitrary files via a crafted request result read function of the diagnostic component.

This vulnerability is known as CVE-2025-66737 since 12/08/2025. The exploitation appears to be easy. The attack can be launched remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 12/26/2025). The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-205448). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.3

VulDB Base Score: 6.3
VulDB Temp Score: 6.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Path traversal
CWE: CWE-22
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

12/08/2025 CVE reserved
12/26/2025 +18 days Advisory disclosed
12/26/2025 +0 days VulDB entry created
12/26/2025 +0 days VulDB entry last update

Sourcesinfo

Status: Not defined

CVE: CVE-2025-66737 (🔒)
GCVE (CVE): GCVE-0-2025-66737
GCVE (VulDB): GCVE-100-338467
EUVD: 🔒

Entryinfo

Created: 12/26/2025 19:07
Updated: 12/26/2025 21:49
Changes: 12/26/2025 19:07 (52), 12/26/2025 21:49 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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