What is CVE-2021-25309?

CVE-2021-25309 is a critical-severity vulnerability in Gigaset Dx600a, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 9.8/10. Published 2021-03-02.

How severe is CVE-2021-25309?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Vulnerability in Gigaset Dx600a

CVE-2021-25309

The telnet administrator service running on port 650 on Gigaset DX600A v41.00-175 devices does not implement any lockout or throttling functionality. This situation (together with the weak password policy that forces a 4-digit password) allows remote attackers to easily obtain administrative access via brute-force attacks.

Published 2021-03-02 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.014 (71.4th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 71st percentile — 71.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.014 · change: +0.000

Affected products

Gigaset Dx600a
Gigaset Dx600a Firmware — versions v41.00-175

Weakness classification (CWE)

References

research.nccgroup.com/2021/02/28/technical-advisory-administrative-passcode-rec… (Third Party Advisory)

Frequently asked questions

What is CVE-2021-25309?: CVE-2021-25309 is a critical-severity vulnerability in Gigaset Dx600a, classified under Improper Restriction of Excessive Authentication Attempts. CVSS score: 9.8/10. Published 2021-03-02.
How severe is CVE-2021-25309?: Critical severity. CVSS v3 base score is 9.8 out of 10.