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Unified Computing SystemApplication · Cisco

CVE-2017-6633

HIGH · 7.5 CVSS v3.0 Published 2017-05-22
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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 · unedited
A vulnerability in the TCP throttling process of Cisco UCS C-Series Rack Servers 3.0(0.234) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient rate-limiting protection. An attacker could exploit this vulnerability by sending a high rate of TCP SYN packets to a specific TCP listening port on an affected device. An exploit could allow the attacker to cause a specific TCP listening port to stop accepting new connections, resulting in a DoS condition. Cisco Bug IDs: CSCva65544.

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 confidence

A vulnerability in the TCP throttling process of Cisco UCS C-Series Rack Servers version 3.0(0.234) allows an unauthenticated remote attacker to cause denial of service. The vulnerability stems from insufficient rate-limiting protection, where an attacker can send a high rate of TCP SYN packets to a specific listening port, causing that port to stop accepting new connections.

MitigationApply the vendor patch from Cisco for CSCva65544, which updates the TCP throttling mechanism to properly rate-limit incoming SYN packets. Until patched, consider implementing external TCP SYN flood protection such as a WAF or dedicated anti-DDoS solution.

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
Unified Computing SystemApplication
Affected:= 3.0\(0.234\)

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
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the Cisco UCS C-Series firmware version
    Access the Cisco UCS Manager or use the UCSM CLI command 'show version' or check via IPMI/BMC web interface to determine the installed firmware version
    Affected if The firmware version is exactly 3.0(0.234)
  2. Confirm the UCS C-Series model
    Verify the server model via UCS Manager, BMC web interface, or physical label. Confirm it is a C-Series Rack Server model
    Affected if The device is a Cisco UCS C-Series Rack Server running the affected version
  3. Identify exposed TCP listening ports
    Use netstat -tan or nmap -sT <server_ip> to enumerate TCP ports in LISTEN state on the management and application interfaces
    Affected if TCP listening services are bound to network-accessible interfaces
  4. Assess network accessibility of listening services
    Review firewall rules, ACLs, and network segmentation to determine if the TCP listening ports are reachable from untrusted networks
    Affected if TCP listening ports are reachable from external or untrusted networks

You are affected only if your Cisco UCS C-Series Rack Server runs exactly firmware version 3.0(0.234) and has TCP listening ports exposed to the network where an attacker could send TCP SYN packets.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor patch from Cisco for CSCva65544, which updates the TCP throttling mechanism to properly rate-limit incoming SYN packets. Until patched, consider implementing external TCP SYN flood protection such as a WAF or dedicated anti-DDoS solution.

Fix this in Unified Computing System Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-6633 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data