Ios XeOperating system · Cisco
CVE-2020-3407
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 RESTCONF and NETCONF-YANG access control list (ACL) function of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the device to reload. The vulnerability is due to incorrect processing of the ACL that is tied to the RESTCONF or NETCONF-YANG feature. An attacker could exploit this vulnerability by accessing the device using RESTCONF or NETCONF-YANG. A successful exploit could allow an attacker to cause the device to reload, resulting in a denial of service (DoS) condition.
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 vulnerability in the RESTCONF and NETCONF-YANG ACL function of Cisco IOS XE Software allows an unauthenticated remote attacker to cause device reload by exploiting incorrect processing of the ACL tied to these management interfaces, resulting in denial of service.
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
= 15.8\(3\)m3CVSS 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
- None
- Scope
- Changed
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/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 device OSRun 'show version' or 'show inventory' to confirm the device runs Cisco IOS XE softwareAffected if The device is not running Cisco IOS XE, then it is not affected by this specific CVE
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Check the IOS XE versionRun 'show version' and locate the software version number (e.g., 15.8(3)m3)Affected if The installed version matches 15.8(3)m3 exactly, the device is in the affected version range
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Verify RESTCONF is enabledRun 'show ip http server status' or 'show restconf operations' to check if the RESTCONF service is activeAffected if RESTCONF is enabled and the IOS XE version is 15.8(3)m3, the device is vulnerable
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Verify NETCONF-YANG is enabledRun 'show netconf-yang status' or 'show netconf-yang sessions' to check if the NETCONF-YANG service is activeAffected if NETCONF-YANG is enabled and the IOS XE version is 15.8(3)m3, the device is vulnerable
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Review ACL applied to management interfacesRun 'show ip access-lists' and check the configuration for interface definitions tied to RESTCONF (port 443) and NETCONF-YANG (port 830)Affected if An ACL exists on the management interface but is incorrectly processed, combined with enabled RESTCONF/NETCONF-YANG on the affected version, exploitation is possible
A user is affected if the device runs Cisco IOS XE version 15.8(3)m3 and has either RESTCONF or NETCONF-YANG interfaces enabled, regardless of ACL configuration due to the incorrect processing flaw.
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 or patch. If unavailable, restrict access to RESTCONF and NETCONF-YANG interfaces to trusted management networks and review ACL configurations.
Fix this in Ios Xe
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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 locallyCheck whether your project pulls in CVE-2020-3407 — 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-2020-3407 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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