iOSOperating system · Cisco
CVE-2019-12670
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 filesystem of Cisco IOS XE Software could allow an authenticated, local attacker within the IOx Guest Shell to modify the namespace container protections on an affected device. The vulnerability is due to insufficient file permissions. An attacker could exploit this vulnerability by modifying files that they should not have access to. A successful exploit could allow the attacker to remove container protections and perform file actions outside the namespace of the container.
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 confidenceThis is a local container escape vulnerability in Cisco IOS XE Software where the IOx Guest Shell container has insufficient file permissions. An authenticated attacker within the IOx Guest Shell can modify files to remove container namespace protections, allowing them to perform file operations outside the container's isolated namespace.
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
iOSOperating system
= 16.10.1CVSS 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
- Local
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:H/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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Verify IOx Guest Shell is enabledExecute 'show iox' or 'show guestshell' from the IOS XE CLI to confirm IOx/Guest Shell feature is active on the deviceAffected if IOx Guest Shell is running or deployed on the device
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Confirm the IOS XE versionRun 'show version' to display the installed Cisco IOS XE software version and compare it to 16.10.1Affected if The installed version equals exactly 16.10.1
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Check Guest Shell filesystem permissionsFrom within the Guest Shell container, run 'ls -la /' and inspect file permissions. Specifically look at critical system directories and files for world-writable permissions or missing immutable flagsAffected if Any system files or directories in the Guest Shell have overly permissive permissions (such as world-writable) that would allow modification to escape namespace isolation
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Test namespace isolation boundaryFrom inside the Guest Shell, attempt to access device filesystem paths outside the container namespace (such as checking if paths like /tftpboot or /bootflash are accessible when they should be isolated)Affected if Files or directories outside the container's isolated namespace are readable or writable from within the Guest Shell
A device is affected if it runs Cisco IOS XE version 16.10.1, has IOx Guest Shell enabled, and the Guest Shell filesystem allows access to files outside its isolated container namespace.
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 Cisco IOS XE software update that patches the file permission vulnerability in the IOx Guest Shell filesystem. Restrict access to the IOx Guest Shell to trusted, privileged users until the patch is applied.
Fix this in iOS
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-12670 — 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-2019-12670 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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