Is CVE-2025-66737 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2025-66737 being exploited in the wild.

How severe is CVE-2025-66737?

Medium severity, with a CVSS score of 4.3, published 26 December 2025.

Which products and versions are affected?

Yealink Sip-T21\(P\)E2 Firmware 52.84.0.15.

Is there a fix for CVE-2025-66737?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2025-66737 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2025-66737?

Check whether you run Yealink Sip-T21\(P\)E2 or Yealink Sip-T21\(P\)E2 Firmware at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2025-66737: Yealink T21P_E2 directory traversal in diagnostic component

CVE-2025-66737 · Severity: medium · CVSS 4.3 · Published 2025-12-26

Yealink T21P_E2 IP phones, commonly used for business telecommunications, contain a security flaw in their diagnostic tools. An authorized user on the network can exploit this to access sensitive internal system files that should normally be restricted. This could lead to the exposure of configuration details or other private device information.

Vendors: Yealink.

Quick answers

Is CVE-2025-66737 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2025-66737 being exploited in the wild.
How severe is CVE-2025-66737?: Medium severity, with a CVSS score of 4.3, published 26 December 2025.
Which products and versions are affected?: Yealink Sip-T21\(P\)E2 Firmware 52.84.0.15.
Is there a fix for CVE-2025-66737?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2025-66737 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2025-66737?: Check whether you run Yealink Sip-T21\(P\)E2 or Yealink Sip-T21\(P\)E2 Firmware at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A directory traversal vulnerability (CWE-23) exists in the diagnostic component of Yealink T21P_E2 IP phones running firmware version 52.84.0.15. The flaw resides in the 'result read' function, which fails to properly sanitize user-supplied input paths. An authenticated attacker with 'normal' privileges can send a specially crafted network request to bypass directory restrictions and read arbitrary files from the underlying operating system. While the attack requires valid credentials, it allows for the unauthorized retrieval of sensitive system information. A proof-of-concept has been identified in public disclosures.

Affected products

Yealink SIP-T21(P) E2 firmware 52.84.0.15

Timeline

2025-12-26: disclosed: Initial NVD publication
2025-12-27: other: CISA-ADP assessment and SSVC enrichment added

References

https://drive.google.com/file/d/1MpxnCL4koKupqWWDmY3ljlybjIPD8ieD/view?usp=sharing

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