What is CVE-2021-1278?

CVE-2021-1278 is a high-severity vulnerability in Cisco Catalyst Sd-Wan Manager, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 8.6/10. Published 2021-01-20.

How severe is CVE-2021-1278?

High severity. CVSS v3 base score is 8.6 out of 10.

Buffer overflow in Cisco Catalyst Sd-Wan Manager

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.

Vulnerability class: Buffer Overflow

Published 2021-01-20 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.017 (76.7th percentile), scored 2026-10-24.

Low probability of exploitation in the next 30 days, but still tracked. 77th percentile — 76.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: +0.000

Affected products

Cisco Catalyst Sd-Wan Manager
Cisco Sd-Wan Solution
Cisco iOS Xe Sd-Wan
Cisco Sd-Wan Firmware — versions 18.3.5, 18.3.8, 18.4.1
Cisco Sd-Wan Vbond Orchestrator
Cisco Sd-Wan Vsmart Controller Firmware
Cisco Vedge 1000 Router
Cisco Vedge 100b Router
Cisco Vedge 100m Router
Cisco Vedge 100 Router

Weakness classification (CWE)

References

tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-do… (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2021-1278?: CVE-2021-1278 is a high-severity vulnerability in Cisco Catalyst Sd-Wan Manager, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 8.6/10. Published 2021-01-20.
How severe is CVE-2021-1278?: High severity. CVSS v3 base score is 8.6 out of 10.