How severe is CVE-2021-40521?

CVE-2021-40521 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-40521 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (90th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40521?

CVE-2021-40521 primarily affects Airangel Hsmx-app-25 Firmware. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-40521?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-40521 published?

CVE-2021-40521 was published on 2021-11-10 and last updated on 2026-06-17.

CVE-2021-40521

CVE-2021-40521 is a critical-severity vulnerability in Airangel Hsmx-app-25 Firmware with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 10.0
EPSS exploit prediction: 4% (90th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Airangel Hsmx-app-25 Firmware
Published: 2021-11-10
Last modified: 2026-06-17

Description

Airangel HSMX Gateway devices through 5.2.04 allow Remote Code Execution.

Frequently asked questions

What is CVE-2021-40521?: Airangel HSMX Gateway devices through 5.2.04 allow Remote Code Execution.
How severe is CVE-2021-40521?: CVE-2021-40521 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-40521 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (90th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40521?: CVE-2021-40521 primarily affects Airangel Hsmx-app-25 Firmware. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-40521?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-40521 published?: CVE-2021-40521 was published on 2021-11-10 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:o:airangel:hsmx-app-25_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:airangel:hsmx-app-100_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:airangel:hsmx-app-1000_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:airangel:hsmx-app-5000_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:airangel:hsmx-app-20000_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Airangel Hsmx-app-25 Firmware

CVE-2021-40519 — Critical (CVSS 10.0): Airangel HSMX Gateway devices through 5.2.04 have Hard-coded Database Credentials.
CVE-2021-40520 — Critical (CVSS 9.8): Airangel HSMX Gateway devices through 5.2.04 have Weak SSH Credentials.
CVE-2021-40518 — Medium (CVSS 6.5): Airangel HSMX Gateway devices through 5.2.04 allow CSRF.
CVE-2021-40517 — Medium (CVSS 5.4): Airangel HSMX Gateway devices through 5.2.04 is vulnerable to stored Cross Site Scripting. XSS Payload is placed in the…

All CVEs affecting Airangel Hsmx-app-25 Firmware →