How severe is CVE-2021-25666?

CVE-2021-25666 has a CVSS 3.x base score of 4.3, 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 low.

Is CVE-2021-25666 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-25666?

CVE-2021-25666 primarily affects Siemens Scalance W780 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-2021-25666?

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

When was CVE-2021-25666 published?

CVE-2021-25666 was published on 2021-02-09 and last updated on 2026-06-17.

CVE-2021-25666

CVE-2021-25666 is a medium-severity vulnerability in Siemens Scalance W780 Firmware with a CVSS 3.x base score of 4.3. 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-770.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
CVSS v2: 3.3
EPSS exploit prediction: 1% (48th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Siemens Scalance W780 Firmware
Published: 2021-02-09
Last modified: 2026-06-17

Description

A vulnerability has been identified in SCALANCE W780 and W740 (IEEE 802.11n) family (All versions < V6.3). Sending specially crafted packets through the ARP protocol to an affected device could cause a partial denial-of-service, preventing the device to operate normally for a short period of time.

Frequently asked questions

What is CVE-2021-25666?: A vulnerability has been identified in SCALANCE W780 and W740 (IEEE 802.11n) family (All versions < V6.3). Sending specially crafted packets through the ARP protocol to an affected device could cause a partial denial-of-service, preventing the device to operate normally for a short period of time.
How severe is CVE-2021-25666?: CVE-2021-25666 has a CVSS 3.x base score of 4.3, 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 low.
Is CVE-2021-25666 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (48th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-25666?: CVE-2021-25666 primarily affects Siemens Scalance W780 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-2021-25666?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-25666 published?: CVE-2021-25666 was published on 2021-02-09 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:o:siemens:scalance_w780_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_w740_firmware:*:*:*:*:*:*:*:*

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