iOSOperating system · Cisco
CVE-2018-15377
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 Cisco Network Plug and Play agent, also referred to as the Cisco Open Plug-n-Play agent, of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a memory leak on an affected device. The vulnerability is due to insufficient input validation by the affected software. An attacker could exploit this vulnerability by sending invalid data to the Cisco Network Plug and Play agent on an affected device. A successful exploit could allow the attacker to cause a memory leak on the affected device, which could cause the device to reload.
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 memory leak vulnerability exists in the Cisco Open Plug-n-Play (NPnP) agent of Cisco IOS and IOS XE Software due to insufficient input validation. An unauthenticated remote attacker can send specially crafted invalid data to the NPnP agent, causing a memory leak that eventually leads to device reload and 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
iOSOperating system
= 15.7\(3.1s\)m= denali-16.3.6= everest-16.5.1CVSS 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
- 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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Check the Cisco iOS or IOS XE versionRun 'show version' and locate the version string in the outputAffected if The version matches or falls within these strings: 15.7(3.1s)m, denali-16.3.6, or everest-16.5.1 (exact version matches only)
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Verify if the NPnP (Plug-n-Play) feature is enabledRun 'show running-config | include pnp' to check for NPnP configuration linesAffected if NPnP configuration lines are present, indicating the feature is enabled on the device
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Confirm the NPnP agent service is activeRun 'show pnp profile' or check if the NPnP process is running via 'show process | include pnp'Affected if The NPnP service or process is active and running on the device
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Check if TCP port 443 is listening for NPnP connectionsRun 'show control-plane host open-ports' or 'show tcp brief' to identify services listening on port 443Affected if The device is listening on TCP port 443 for NPnP agent connections
A device is affected if it runs a matching iOS/IOS XE version (15.7(3.1s)m, denali-16.3.6, or everest-16.5.1) AND has the NPnP agent feature enabled and accessible on the network.
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 security patch for this vulnerability; as an interim measure, restrict network access to the NPnP agent port (default TCP 443) using ACLs to prevent unauthorized external attackers from reaching the service.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation12.0 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 $6,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-15377 — 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-2018-15377 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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