dbcve.org
Asr 5000 SoftwareOperating system · Cisco

CVE-2016-6455

HIGH · 7.5 CVSS v3.0 Published 2016-11-03
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 Slowpath of StarOS for Cisco ASR 5500 Series routers with Data Processing Card 2 (DPC2) could allow an unauthenticated, remote attacker to cause a subset of the subscriber sessions to be disconnected, resulting in a partial denial of service (DoS) condition. This vulnerability affects Cisco ASR 5500 devices with Data Processing Card 2 (DPC2) running StarOS 18.0 or later. More Information: CSCvb12081. Known Affected Releases: 18.7.4 19.5.0 20.0.2.64048 20.2.3 21.0.0. Known Fixed Releases: 18.7.4 18.7.4.65030 18.8.M0.65044 19.5.0 19.5.0.65092 19.5.M0.65023 19.5.M0.65050 20.2.3 20.2.3.64982 20.2.3.65017 20.2.a4.65307 20.3.M0.64984 20.3.M0.65029 20.3.M0.65037 20.3.M0.65071 20.3.T0.64985 20.3.T0.65031 20.3.T0.65043 20.3.T0.65067 21.0.0 21.0.0.65256 21.0.M0.64922 21.0.M0.64983 21.0.M0.65140 21.0.V0.65150 21.1.A0.64932 21.1.A0.64987 21.1.A0.65145 21.1.PP0.65270 21.1.R0.65130 21.1.R0.65135 21.1.R0.65154 21.1.VC0.65203 21.2.A0.65147.

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 confidence

A vulnerability in the Slowpath processing of StarOS on Cisco ASR 5500 Series routers with Data Processing Card 2 (DPC2) allows an unauthenticated remote attacker to disconnect a subset of subscriber sessions, resulting in partial denial of service. The issue affects StarOS 18.0 and later versions running on affected hardware.

MitigationApply the appropriate fixed StarOS release (such as 18.7.4.65030, 19.5.0.65092, 20.2.3.64982, or later versions) to all affected Cisco ASR 5500 devices with DPC2 cards.

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
Asr 5000 SoftwareOperating system
Affected:= 18.0.0= 18.0.0.57828= 18.0.0.59167= 18.0.0.59211= 18.0.l0.59219= 18.1.0= 18.1.0.59776= 18.1.0.59780= 18.1_base= 18.3.0= 18.3_base= 18.4.0

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 router hardware platform
    Execute 'show hardware' or 'show chassis' command in StarOS CLI to confirm the device is a Cisco ASR 5500 Series router
    Affected if The hardware is not an ASR 5500 Series router (the vulnerability only affects ASR 5500)
  2. Verify DPC2 card presence
    Execute 'show card' or 'show hardware | include DPC' command to check for presence of Data Processing Card 2 (DPC2) in the chassis
    Affected if No DPC2 cards are installed (the vulnerability only affects systems with DPC2)
  3. Determine the running StarOS version
    Execute 'show version' or 'show software' command in StarOS CLI to display the installed StarOS version number
    Affected if The version displayed matches any of these: 18.0.0, 18.0.0.57828, 18.0.0.59167, 18.0.0.59211, 18.0.l0.59219, 18.1.0, 18.1.0.59776, 18.1.0.59780, 18.1_base, 18.3.0, 18.3_base, 18.4.0
  4. Confirm StarOS release is 18.0 or later
    Review the version output from step 3 to verify the major version is 18.0 or higher
    Affected if The installed version is 18.0 or later (the vulnerability affects StarOS 18.0 and later on affected hardware)

You are affected if you have an ASR 5500 Series router with DPC2 cards running any of these StarOS versions: 18.0.0 through 18.4.0 (specifically 18.0.0, 18.0.0.57828, 18.0.0.59167, 18.0.0.59211, 18.0.l0.59219, 18.1.0, 18.1.0.59776, 18.1.0.59780, 18.1_base, 18.3.0, 18.3_base, or 18.4.0)

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 appropriate fixed StarOS release (such as 18.7.4.65030, 19.5.0.65092, 20.2.3.64982, or later versions) to all affected Cisco ASR 5500 devices with DPC2 cards.

Fix this in Asr 5000 Software Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2016-6455 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