Ios Xe Sd WanOperating system · Cisco

CVE-2021-1278

HIGH · 7.5 CVSS v3.1 Published 2021-01-20

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

84/100

Remediation priority · High

Remotely reachable No privileges Zero-click

Official description

NVD · unedited

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.

Technical summary

dbcve analysis · moderate confidence

Multiple vulnerabilities in Cisco SD-WAN products allow unauthenticated remote attackers to execute denial of service attacks against affected devices. The specific vulnerability types and technical details are not enumerated in the available description, but the CVSS 7.5 rating indicates significant impact potential requiring immediate attention.

MitigationApply Cisco-provided patches for the SD-WAN vulnerabilities; given the unauthenticated remote attack vector, prioritize patching externally-facing SD-WAN devices and implement network segmentation as an interim control if immediate patching is not feasible.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

Ios Xe Sd WanOperating system

Affected:all versions

Sd Wan FirmwareOperating system

Affected:= 18.3.5= 18.3.8= 18.4.1= 18.4.4= 18.4.5= 19.2.0= 19.2.1= 19.2.2= 19.2.99= 20.1.0

Sd Wan Vsmart Controller FirmwareOperating system

Affected:all versions

Catalyst Sd Wan ManagerApplication

Affected:all versions

Sd Wan Vbond OrchestratorApplication

Affected:all versions

CVSS breakdown

From the vector

Attack vector: Network
Complexity: Low
Privileges: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Identify the SD-WAN product component in your environment

Run 'show version' or check the device type/metadata to determine which Cisco SD-WAN component is deployed (IOS XE SD-WAN, SD-WAN Firmware, vSmart Controller, vBond Orchestrator, or SD-WAN Manager)

Affected if The device is any of these five SD-WAN components and has not been patched
Check the installed SD-WAN Firmware version

Execute 'show version' or 'show sdwan version' to retrieve the firmware version number

Affected if The version is exactly 18.3.5, 18.3.8, 18.4.1, 18.4.4, 18.4.5, 19.2.0, 19.2.1, 19.2.2, 19.2.99, or 20.1.0
Verify IOS XE SD-WAN version

Run 'show version' on the IOS XE SD-WAN device and note the software version

Affected if The device runs IOS XE SD-WAN at any version (all versions are affected)
Check vSmart Controller and vBond Orchestrator versions

Run 'show version' or 'show controller vbond' to identify the version of these control plane components

Affected if These components are present at any version (all versions affected)

Your environment is affected if any device runs one of the listed SD-WAN Firmware versions, or runs IOS XE SD-WAN, vSmart Controller, vBond Orchestrator, or SD-WAN Manager at any version without the Cisco patch applied.

Generated from the published advisory. Verify against your own configuration.

Remediation

From vendor data

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Apply Cisco-provided patches for the SD-WAN vulnerabilities; given the unauthenticated remote attack vector, prioritize patching externally-facing SD-WAN devices and implement network segmentation as an interim control if immediate patching is not feasible.

Fix this in Ios Xe Sd Wan Scoped from the published advisory

Consultation4.0 h
Implementation8.0 h
Testing6.0 h
Review / QA4.0 h

22.0 hours of engineering $3,860

Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

Scan for this in your stack

Free · runs locally

dbcve dependency scanner

Check whether your project pulls in CVE-2021-1278 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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References

Primary sources

tools.cisco.comVendor Advisory
nvd.nist.govNVD record

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-1278 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2021-1278?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
No spam, self-promotion, credentials, or personal data

At a glance

A fix existsA vendor remedy is published

Severity 7.5 High

Exploit likelihood EPSS, next 30 days 1.7%

Affects: Ios Xe Sd Wan

Remediation

A high-priority fix

Fix this in Ios Xe Sd Wan 22 hrs · Moderate

Typical engagement from $3,860

Get a fix See the full breakdown ↓

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2021-1278 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

Check your environment

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References