Virtual Topology SystemApplication · Cisco
CVE-2015-6377
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 · uneditedCisco Virtual Topology System (VTS) 2.0(0) and 2.0(1) allows remote attackers to cause a denial of service (CPU and memory consumption, and TCP port outage) via a flood of crafted TCP packets, aka Bug ID CSCux13379.
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 · moderate confidenceCisco Virtual Topology System (VTS) versions 2.0(0) and 2.0(1) are vulnerable to a denial-of-service attack via a flood of crafted TCP packets. The attack causes excessive CPU and memory consumption, resulting in TCP port outage and service unavailability.
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
Virtual Topology SystemApplication
= 2.0\(0\)= 2.0\(1\)CVSS 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
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:N/AC:L/Au:N/C:N/I:N/A:C
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 VTS is installedCheck your systems for the presence of Cisco Virtual Topology System. This is typically deployed as a virtual machine. Verify the product name in your inventory or by logging into the system and checking the installed software.Affected if The product is present on your network
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Identify the installed VTS versionAccess the VTS admin interface or use the command-line interface to retrieve the software version. Look for version information in the system About or version display.Affected if The version displayed is 2.0(0) or 2.0(1)
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Verify TCP services are exposedCheck if VTS TCP ports are accessible from network locations where the attack could originate. Scan or review firewall rules for open ports on the VTS system.Affected if TCP services are externally accessible without filtering
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Review for DoS symptomsMonitor VTS system resources (CPU and memory usage) and check for service availability issues. Look for unexplained TCP port outages or service unavailability.Affected if Excessive CPU/memory consumption or TCP port outages are observed and the version is 2.0(0) or 2.0(1)
Your environment is affected if Cisco VTS version 2.0(0) or 2.0(1) is installed and has accessible TCP services that could receive the malicious packet flood.
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 available Cisco patches for VTS or upgrade to a non-vulnerable version. If patches are unavailable (product EOL), implement network-level filtering/ACLs to block malicious TCP traffic at perimeter firewalls or IDS/IPS systems.
Fix this in Virtual Topology System
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-6377 — 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-2015-6377 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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