What is CVE-2021-40521?

CVE-2021-40521 is a critical-severity vulnerability in Airangel Hsmx-App-100. CVSS score: 9.8/10. Published 2021-11-10.

How severe is CVE-2021-40521?

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

Vulnerability in Airangel Hsmx-App-100

CVE-2021-40521

Airangel HSMX Gateway devices through 5.2.04 allow Remote Code Execution.

Published 2021-11-10 · 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: 0.045 (91.2th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 91st percentile — 91.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.043 · newest: 0.045 · change: +0.001

Affected products

References

airangel.com/hsmx-gateway/ (Product)
etizazmohsin.com/hsmx.html (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-40521?: CVE-2021-40521 is a critical-severity vulnerability in Airangel Hsmx-App-100. CVSS score: 9.8/10. Published 2021-11-10.
How severe is CVE-2021-40521?: Critical severity. CVSS v3 base score is 9.8 out of 10.