Ios XeOperating system · Cisco
CVE-2020-3400
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 UI feature of Cisco IOS XE Software could allow an authenticated, remote attacker to utilize parts of the web UI for which they are not authorized.The vulnerability is due to insufficient authorization of web UI access requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the web UI. A successful exploit could allow the attacker to utilize parts of the web UI for which they are not authorized. This could allow a Read-Only user to perform actions of an Admin user.
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 confidenceA privilege escalation vulnerability in Cisco IOS XE Web UI allows authenticated Read-Only users to bypass authorization checks via crafted HTTP requests, enabling them to perform Admin-level actions they are not entitled to execute.
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
Ios XeOperating system
= 16.2.2= 16.3.1= 16.3.1a= 16.3.2= 16.3.3= 16.3.4= 16.3.5= 16.3.5b= 16.3.6= 16.3.7= 16.3.8= 16.3.9CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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 the Cisco IOS XE versionRun 'show version' or 'show version | include IOS XE' to retrieve the installed software versionAffected if The version matches one of these: 16.2.2, 16.3.1, 16.3.1a, 16.3.2, 16.3.3, 16.3.4, 16.3.5, 16.3.5b, 16.3.6, 16.3.7, 16.3.8, 16.3.9
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Confirm the Web UI feature is enabledRun 'show running-config | include ip http server|ip https server' to check if HTTP or HTTPS server is activeAffected if HTTP or HTTPS server is enabled, exposing the Web UI interface
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Check for Read-Only privilege accountsRun 'show users' or review local user configurations with 'show running-config | include username' to identify accounts with privilege level 1 (Read-Only)Affected if One or more Read-Only (privilege level 1) user accounts exist in the system
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Review logs for privilege escalation activityExamine system logs or use 'show logging' looking for admin-level command execution from users with privilege level 1Affected if Logs show Read-Only users executing commands or accessing features reserved for Admin (privilege level 15) users
A user is affected if the device runs a matched IOS XE version from the list, the Web UI is enabled, and Read-Only users exist in the environment.
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 relevant Cisco IOS XE software update when available. Until patched, restrict web UI access to trusted networks using ACLs and ensure account privileges follow least-privilege principles.
Fix this in Ios Xe
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,888.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-3400 — 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-2020-3400 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
- No weaponised exploit code, or anything meant to cause harm
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