Sd WanApplication · Cisco
CVE-2020-27128
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.
NVD · uneditedA vulnerability in the application data endpoints of Cisco SD-WAN vManage Software could allow an authenticated, remote attacker to write arbitrary files to an affected system. The vulnerability is due to improper validation of requests to APIs. An attacker could exploit this vulnerability by sending malicious requests to an API within the affected application. A successful exploit could allow the attacker to conduct directory traversal attacks and write files to an arbitrary location on the targeted system.
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.
dbcve analysis · high confidenceCisco SD-WAN vManage Software contains a file write vulnerability in application data endpoints. An authenticated attacker can exploit improper API input validation to perform directory traversal attacks and write arbitrary files to any location on the affected system.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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.
NVD · CPE data
Sd WanApplication
< 20.3.1CVSS 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.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
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.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Cisco SD-WAN vManage versionAccess the vManage admin interface or use the CLI command 'show version' to retrieve the installed software version numberAffected if The installed version is earlier than 20.3.1 (for example, 20.1.x, 19.x, or earlier)
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Verify API access is enabledConfirm that the vManage REST API service is accessible on the device. Check if API endpoints respond to HTTP/HTTPS requests at the vManage hostAffected if API endpoints are reachable and the attacker could send authenticated requests to application data endpoints
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Check for directory traversal in API logsReview vManage system logs and API request logs for patterns indicating directory traversal attempts (such as '../' or '..\' sequences in API request parameters)Affected if Unusual directory traversal patterns appear in API logs, indicating potential exploitation attempts
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Verify application data endpoint configurationInspect the vManage API configuration and confirm that application data endpoints are exposed. These typically include endpoints under /dataservice/ or similar application data pathsAffected if Application data API endpoints are exposed and accessible to authenticated users
A system is affected if it runs Cisco SD-WAN vManage software version earlier than 20.3.1 and has accessible API endpoints that accept authenticated requests to application data endpoints.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor data20.3.1
Apply the Cisco vendor patch for CVE-2020-27128, which corrects the improper input validation in the API endpoints. Upgrade to a fixed version of SD-WAN vManage software as specified in Cisco's security advisory.
Fix this in Sd Wan
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-27128 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-27128 in production — separate from our analysis above.
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
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- Version or environment caveats, and links to real fixes
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