How severe is CVE-2025-40556?

CVE-2025-40556 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2025-40556 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2025-40556?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-40556 have an EU (EUVD) identifier?

Yes. CVE-2025-40556 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-14681.

When was CVE-2025-40556 published?

CVE-2025-40556 was published on 2025-05-13 and last updated on 2026-06-17.

CVE-2025-40556

CVE-2025-40556 is a medium-severity vulnerability with a CVSS 3.x base score of 6.5. 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-20.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 7.1
EPSS exploit prediction: 0% (11th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-14681
Weakness: CWE-20
Published: 2025-05-13
Last modified: 2026-06-17

Description

A vulnerability has been identified in BACnet ATEC 550-440 (All versions), BACnet ATEC 550-441 (All versions), BACnet ATEC 550-445 (All versions), BACnet ATEC 550-446 (All versions). Affected devices improperly handle specific incoming BACnet MSTP messages. This could allow an attacker residing in the same BACnet network to send a specially crafted MSTP message that results in a denial of service condition of the targeted device. A power cycle is required to restore the device's normal operation.

Frequently asked questions

What is CVE-2025-40556?: A vulnerability has been identified in BACnet ATEC 550-440 (All versions), BACnet ATEC 550-441 (All versions), BACnet ATEC 550-445 (All versions), BACnet ATEC 550-446 (All versions). Affected devices improperly handle specific incoming BACnet MSTP messages. This could allow an attacker residing in the same BACnet network to send a specially crafted MSTP message that results in a denial of service condition of the targeted device. A power cycle is required to restore the device's normal operation.
How severe is CVE-2025-40556?: CVE-2025-40556 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-40556 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-40556?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-40556 have an EU (EUVD) identifier?: Yes. CVE-2025-40556 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-14681.
When was CVE-2025-40556 published?: CVE-2025-40556 was published on 2025-05-13 and last updated on 2026-06-17.

References

https://cert-portal.siemens.com/productcert/html/ssa-828116.html

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