UmbrellaApplication · Cisco
CVE-2020-3337
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 web server of Cisco Umbrella could allow an unauthenticated, remote attacker to redirect a user to an undesired web page. The vulnerability is due to improper input validation of the URL parameters in an HTTP request that is sent to an affected device. An attacker could exploit this vulnerability by sending a crafted HTTP request that could cause the web application to redirect the request to a specified malicious URL. A successful exploit could allow the attacker to redirect a user to a malicious website.
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 confidenceOpen redirect vulnerability in Cisco Umbrella's web server allows unauthenticated remote attackers to craft malicious HTTP requests with specially manipulated URL parameters that cause the application to redirect users to attacker-controlled websites instead of legitimate destinations.
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
UmbrellaApplication
all versionsCVSS 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
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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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Confirm Cisco Umbrella is in useInspect your network configuration, proxy settings, or DNS records for references to 'umbrella.com' or the Cisco Umbrella service. Check if your organization uses Cisco Umbrella for DNS filtering or web security.Affected if Your environment routes DNS queries or web traffic through Cisco Umbrella services
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Identify the Umbrella dashboard URLLocate the web interface URL your organization uses to access Cisco Umbrella (typically something like 'dashboard.umbrella.com' or a custom domain).Affected if You have an active Cisco Umbrella management interface accessible on the web
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Test for open redirect with a crafted URLSend an HTTP request to the Umbrella web interface with a manipulated redirect parameter pointing to an external domain (for example, appending '?redirect=http://attacker.com' or similar URL parameter patterns used by the application). Inspect the HTTP response for a Location header pointing to the attacker-controlled domain.Affected if The application redirects to a URL you control rather than remaining within the legitimate Umbrella domain
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Examine browser-based redirect behaviorIf you have access to a test Umbrella account, attempt to log in and observe whether clicking internal links or being redirected after actions causes unexpected navigation to external domains outside the umbrella.com namespace.Affected if Legitimate Umbrella workflows redirect users to domains not owned by Cisco
If your organization uses Cisco Umbrella and you observe unauthorized redirects to external domains when interacting with its web interface, your environment is affected by this open redirect vulnerability.
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 dataApply the vendor patch from Cisco when available. In the interim, users should exercise caution with links appearing to originate from Umbrella and verify URL destinations before clicking.
Fix this in Umbrella
Scoped from the published advisory
- Consultation2.0 h
- Implementation3.0 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 $3,040.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3337 — 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-2020-3337 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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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.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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