Yealink IP Phones and RPS (Redirect and Provisioning Service)

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1. EXECUTIVE SUMMARY

• CVSS v4 5.3
• ATTENTION: Exploitable remotely/Low attack complexity
• Vendor: Yealink
• Equipment: IP Phones
• Vulnerability: Improper Restriction of Excessive Authentication Attempts, Allocation of Resources Without Limits or Throttling, Incorrect Authorization, Improper Certificate Validation

2. RISK EVALUATION

Successful exploitation of these vulnerabilities could result in an information disclosure.

3. TECHNICAL DETAILS

3.1 AFFECTED PRODUCTS

The following versions of Yealink IP products are affected:

• SIP-T19P_E2: Versions prior to 53.84.0.121
• SIP-T21P_E2: Versions prior to 52.84.0.121
• SIP-T23G: Versions prior to 44.84.0.121
• SIP-T40G: Versions prior to 76.84.0.121
• SIP-T40P: Versions prior to 54.84.0.121
• SIP-T27G: Versions prior to 69.84.0.121
• SIP-T41S: Versions prior to 66.84.0.121
• SIP-T42S: Versions prior to 66.84.0.121
• SIP-T46S: Versions prior to 66.84.0.121
• SIP- T48S: Versions prior to 66.84.0.121
• SIP-CP920: Versions prior to 78.84.0.121
• SIP-T53: Versions prior to X.84.0.121
• SIP-T53W: Versions prior to X.84.0.121
• SIP-T54W: Versions prior to X.84.0.121
• SIP-T57W: Versions prior to X.84.0.121
• SIP-T56A: Versions prior to 58.84.0.37
• SIP-T58: Versions prior to 58.84.0.37
• W52P: Versions prior to 25.81.0.67
• W60B: Versions prior to 77.83.0.83
• CP960: Versions prior to 73.84.0.37
• SIP-T27P: Version 45.83.0.160 and prior
• SIP-T29G: Version 46.83.0.160 and prior
• SIP-T41P: Version 36.83.0.160 and prior
• SIP-T42G: Version 29.83.0.160 and prior
• SIP-T46G: Version 28.83.0.160 and prior
• SIP-T48G: Version 35.83.0.160 and prior
• SIP-T20P: All versions
• SIP-T22P: All versions
• SIP-T26P: All versions
• SIP-T27P: All versions
• T52S: All versions
• T54S: All versions
• RPS (Redirect and Provisioning Service): All builds prior to 05-26-2025

3.2 VULNERABILITY OVERVIEW

3.2.1 IMPROPER RESTRICTION OF EXCESSIVE AUTHENTICATION ATTEMPTS CWE-307

The affected products lack serial number verification attempt limits, enabling brute-force enumeration (last five digits).

CVE-2025-52916 has been assigned to this vulnerability. A CVSS v3 base score of 2.2 has been calculated; the CVSS vector string is (AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N).

A CVSS v4 score has also been calculated for CVE-2025-52916. A base score of 2.1 has been calculated; the CVSS vector string is (AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N).

3.2.2 ALLOCATION OF RESOURCES WITHOUT LIMITS OR THROTTLING CWE-770

The affected products lack rate limiting, potentially enabling information disclosure via excessive requests.

CVE-2025-52917 has been assigned to this vulnerability. A CVSS v3 base score of 4.3 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N).

A CVSS v4 score has also been calculated for CVE-2025-52917. A base score of 5.3 has been calculated; the CVSS vector string is (AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N).

3.2.3 INCORRECT AUTHORIZATION CWE-863

The affected products fail to enforce access restrictions on OpenAPIs for frozen enterprise accounts, allowing unauthorized access to deactivated interfaces.

CVE-2025-52918 has been assigned to this vulnerability. A CVSS v3 base score of 5.0 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N).

A CVSS v4 score has also been calculated for CVE-2025-52918. A base score of 5.3 has been calculated; the CVSS vector string is (AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N).

3.2.4 IMPROPER CERTIFICATE VALIDATION CWE-295

The certificate upload function in the affected products does not properly validate certificate content, potentially allowing invalid certificates to be uploaded.

CVE-2025-52919 has been assigned to this vulnerability. A CVSS v3 base score of 4.3 has been calculated; the CVSS vector string is (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N).

A CVSS v4 score has also been calculated for CVE-2025-52919. A base score of 5.3 has been calculated; the CVSS vector string is (AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:L/SI:N/SA:N).

3.3 BACKGROUND

• CRITICAL INFRASTRUCTURE SECTORS: Communications
• COUNTRIES/AREAS DEPLOYED: Worldwide
• COMPANY HEADQUARTERS LOCATION: China

3.4 RESEARCHER

Jeroen Hermans of CloudAware reported these vulnerabilities to CISA.

4. MITIGATIONS

Users of Yealink are encouraged to navigate to Yealink's support portal and update to the following versions:

• SIP-T19P_E2: Version 53.84.0.160 or higher
• SIP-T21P_E2: Version 52.84.0.160 or higher
• SIP-T23G: Version 44.84.0.160 or higher
• SIP-T40G: Version 76.84.0.160 or higher
• SIP-T40P: Version 54.84.0.160 or higher
• SIP-T27G: Version 69.86.0.160 or higher
• SIP-T41S: Version 66.86.0.83 or higher
• SIP-T42S: Version 66.86.0.83 or higher
• SIP-T46S: Version 66.86.0.83 or higher
• SIP- T48S: Version 66.86.0.83 or higher
• SIP-CP920: Version 78.86.0.15 or higher
• SIP-T53: Version 96.86.0.75 or higher
• SIP-T53W: Version 96.86.0.75 or higher
• SIP-T54W: Version 96.86.0.75 or higher
• SIP-T57W: Version 96.86.0.75 or higher
• SIP-T56A: Version 58.86.0.160 or higher
• SIP-T58: Version 58.86.0.160 or higher
• W52P: Version 25.81.0.160 or higher
• W60B: Version 77.85.0.160 or higher
• CP960: Version 73.86.0.160 or higher
• SIP-T27P: Version 45.83.0.161 or higher
• SIP-T29G: Version 46.83.0.160 and prior
• SIP-T41P: Version 36.83.0.160 and prior
• SIP-T42G: Version 29.83.0.160 and prior
• SIP-T46G: Version 28.83.0.160 and prior
• SIP-T48G: Version 35.83.0.160 and prior
• RPS (Redirect and Provisioning Service): Yealink has deployed a fix to all cloud service instances

The following products are no longer receiving RPS support:

• SIP-T20P
• SIP-T22P
• SIP-T26P
• SIP-T27P
• T52S
• T54S

For more information, see the associated Yealink security advisory: Yealink RPS Issue Statement.

CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability, such as:

• Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
• Locate control system networks and remote devices behind firewalls and isolating them from business networks.
• When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices.

CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.

CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.

CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.

Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.

Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.

No known public exploitation specifically targeting these vulnerabilities has been reported to CISA at this time.

5. UPDATE HISTORY

• August 07, 2025: Initial Publication