How severe is CVE-2021-40366?

CVE-2021-40366 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2021-40366 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40366?

CVE-2021-40366 primarily affects Siemens Climatix Pol909 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-40366?

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

When was CVE-2021-40366 published?

CVE-2021-40366 was published on 2021-11-09 and last updated on 2026-06-17.

CVE-2021-40366

CVE-2021-40366 is a high-severity vulnerability in Siemens Climatix Pol909 Firmware with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-319.

Key facts

Severity: High (CVSS 3.x base score 7.4)
CVSS v2: 5.8
EPSS exploit prediction: 0% (33rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-319
Affected product: Siemens Climatix Pol909 Firmware
Published: 2021-11-09
Last modified: 2026-06-17

Description

A vulnerability has been identified in Climatix POL909 (AWB module) (All versions < V11.42), Climatix POL909 (AWM module) (All versions < V11.34). The web server of affected devices transmits data without TLS encryption. This could allow an unauthenticated remote attacker in a man-in-the-middle position to read sensitive data, such as administrator credentials, or modify data in transit.

Frequently asked questions

What is CVE-2021-40366?: A vulnerability has been identified in Climatix POL909 (AWB module) (All versions < V11.42), Climatix POL909 (AWM module) (All versions < V11.34). The web server of affected devices transmits data without TLS encryption. This could allow an unauthenticated remote attacker in a man-in-the-middle position to read sensitive data, such as administrator credentials, or modify data in transit.
How severe is CVE-2021-40366?: CVE-2021-40366 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2021-40366 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40366?: CVE-2021-40366 primarily affects Siemens Climatix Pol909 Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-40366?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-40366 published?: CVE-2021-40366 was published on 2021-11-09 and last updated on 2026-06-17.

References

https://cert-portal.siemens.com/productcert/pdf/ssa-703715.pdf

Affected products (2)

cpe:2.3:o:siemens:climatix_pol909_firmware:*:*:*:*:advanced_web_module:*:*:*
cpe:2.3:o:siemens:climatix_pol909_firmware:*:*:*:*:advanced_web_and_bacnet_module:*:*:*

More vulnerabilities in Siemens Climatix Pol909 Firmware

CVE-2021-41543 — Medium (CVSS 6.5): A vulnerability has been identified in Climatix POL909 (AWB module) (All versions < V11.44), Climatix POL909 (AWM…
CVE-2021-41542 — Medium (CVSS 6.1): A vulnerability has been identified in Climatix POL909 (AWB module) (All versions < V11.44), Climatix POL909 (AWM…
CVE-2021-41541 — Medium (CVSS 6.1): A vulnerability has been identified in Climatix POL909 (AWB module) (All versions < V11.44), Climatix POL909 (AWM…
CVE-2020-7575 — Medium (CVSS 6.1): A vulnerability has been identified in Climatix POL908 (BACnet/IP module) (All versions), Climatix POL909 (AWM module)…
CVE-2020-7574 — Medium (CVSS 6.1): A vulnerability has been identified in Climatix POL908 (BACnet/IP module) (All versions), Climatix POL909 (AWM module)…

All CVEs affecting Siemens Climatix Pol909 Firmware →

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