How severe is CVE-2020-3351?

CVE-2020-3351 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-3351 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-3351?

CVE-2020-3351 primarily affects Cisco Sd-wan Firmware. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-3351?

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-2020-3351 published?

CVE-2020-3351 was published on 2020-07-16 and last updated on 2026-06-17.

CVE-2020-3351

CVE-2020-3351 is a high-severity vulnerability in Cisco Sd-wan Firmware with a CVSS 3.x base score of 8.6. 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-400.

Key facts

Severity: High (CVSS 3.x base score 8.6)
CVSS v2: 7.8
EPSS exploit prediction: 1% (69th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Cisco Sd-wan Firmware
Published: 2020-07-16
Last modified: 2026-06-17

Description

A vulnerability in Cisco SD-WAN Solution Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to improper validation of fields in Cisco SD-WAN peering messages that are encapsulated in UDP packets. An attacker could exploit this vulnerability by sending crafted UDP messages to the targeted system. A successful exploit could allow the attacker to cause services on the device to fail, resulting in a DoS condition that could impact the targeted device and other devices that depend on it.

Frequently asked questions

What is CVE-2020-3351?: A vulnerability in Cisco SD-WAN Solution Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to improper validation of fields in Cisco SD-WAN peering messages that are encapsulated in UDP packets. An attacker could exploit this vulnerability by sending crafted UDP messages to the targeted system. A successful exploit could allow the attacker to cause services on the device to fail, resulting in a DoS condition that could impact the targeted device and other devices that depend on it.
How severe is CVE-2020-3351?: CVE-2020-3351 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-3351 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-3351?: CVE-2020-3351 primarily affects Cisco Sd-wan Firmware. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-3351?: 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-2020-3351 published?: CVE-2020-3351 was published on 2020-07-16 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdw-dos-KWOdyHnB

Affected products (3)

cpe:2.3:o:cisco:sd-wan_firmware:*:*:*:*:*:*:*:*
cpe:2.3:a:cisco:vedge_cloud_router:-:*:*:*:*:*:*:*
cpe:2.3:a:cisco:vsmart_controller:-:*:*:*:*:*:*:*

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