How severe is CVE-2021-1278?

CVE-2021-1278 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-2021-1278 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-1278?

CVE-2021-1278 primarily affects Cisco Ios Xe Sd-wan. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-1278?

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-2021-1278 published?

CVE-2021-1278 was published on 2021-01-20 and last updated on 2026-06-17.

CVE-2021-1278

CVE-2021-1278 is a high-severity vulnerability in Cisco Ios Xe Sd-wan 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-59.

Key facts

Severity: High (CVSS 3.x base score 8.6)
CVSS v2: 7.8
EPSS exploit prediction: 2% (74th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-59
Affected product: Cisco Ios Xe Sd-wan
Published: 2021-01-20
Last modified: 2026-06-17

Description

Multiple vulnerabilities in Cisco SD-WAN products could allow an unauthenticated, remote attacker to execute denial of service (DoS) attacks against an affected device. For more information about these vulnerabilities, see the Details section of this advisory.

Frequently asked questions

What is CVE-2021-1278?: Multiple vulnerabilities in Cisco SD-WAN products could allow an unauthenticated, remote attacker to execute denial of service (DoS) attacks against an affected device. For more information about these vulnerabilities, see the Details section of this advisory.
How severe is CVE-2021-1278?: CVE-2021-1278 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-2021-1278 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-1278?: CVE-2021-1278 primarily affects Cisco Ios Xe Sd-wan. In total, 14 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-1278?: 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-2021-1278 published?: CVE-2021-1278 was published on 2021-01-20 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-dosmulti-48jJuEUP

Affected products (14)

cpe:2.3:o:cisco:ios_xe_sd-wan:-:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:18.3.5:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:18.3.8:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:18.4.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:18.4.4:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:18.4.5:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:19.2.0:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:19.2.1:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:19.2.2:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:19.2.99:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_firmware:20.1.0:*:*:*:*:*:*:*
cpe:2.3:o:cisco:sd-wan_vsmart_controller_firmware:*:*:*:*:*:*:*:*
cpe:2.3:a:cisco:catalyst_sd-wan_manager:-:*:*:*:*:*:*:*
cpe:2.3:a:cisco:sd-wan_vbond_orchestrator:-:*:*:*:*:*:*:*

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