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Asr 5000 Series SoftwareApplication · Cisco

CVE-2017-3819

HIGH · 8.8 CVSS v3.0 Published 2017-03-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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 privilege escalation vulnerability in the Secure Shell (SSH) subsystem in the StarOS operating system for Cisco ASR 5000 Series, ASR 5500 Series, ASR 5700 Series devices, and Cisco Virtualized Packet Core could allow an authenticated, remote attacker to gain unrestricted, root shell access. The vulnerability is due to missing input validation of parameters passed during SSH or SFTP login. An attacker could exploit this vulnerability by providing crafted user input to the SSH or SFTP command-line interface (CLI) during SSH or SFTP login. An exploit could allow an authenticated attacker to gain root privileges access on the router. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. This vulnerability can be triggered via both IPv4 and IPv6 traffic. An established TCP connection toward port 22, the SSH default port, is needed to perform the attack. The attacker must have valid credentials to login to the system via SSH or SFTP. The following products have been confirmed to be vulnerable: Cisco ASR 5000/5500/5700 Series devices running StarOS after 17.7.0 and prior to 18.7.4, 19.5, and 20.2.3 with SSH configured are vulnerable. Cisco Virtualized Packet Core - Single Instance (VPC-SI) and Distributed Instance (VPC-DI) devices running StarOS prior to N4.2.7 (19.3.v7) and N4.7 (20.2.v0) with SSH configured are vulnerable. Cisco Bug IDs: CSCva65853.

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 privilege escalation vulnerability exists in the SSH/SFTP subsystem of Cisco's StarOS operating system. An authenticated remote attacker with valid SSH or SFTP credentials can exploit missing input validation of login parameters to gain unrestricted root shell access on affected ASR 5000/5500/5700 Series routers and Virtualized Packet Core instances.

MitigationUpgrade StarOS to version 18.7.4, 19.5, or 20.2.3 (or later) for ASR devices, or to N4.2.7/N4.7 (or later) for VPC instances. Limit SSH access to trusted management networks and enforce least-privilege user accounts until patching is complete.

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 Series SoftwareApplication
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
Virtualized Packet CoreApplication
Affected:= v18.0_base= v19.0_base= v20.0_base

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

CVSS:3.0/AV:N/AC:L/PR:L/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 checks

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

  1. Identify the StarOS device type
    Run 'show version' or check the system prompt/hostname to determine if the device is an ASR 5000/5500/5700 Series router or a Virtualized Packet Core instance.
    Affected if Device is an ASR 5000/5500/5700 Series router or VPC instance running the listed affected versions.
  2. Determine the installed StarOS version
    Execute 'show version' or 'show software' command to retrieve the installed StarOS version number.
    Affected if Version matches any of the affected ASR versions (18.0.0, 18.0.0.57828, 18.0.0.59167, 18.0.0.59211, 18.0.59219, 18.1.0, 18.1.0.59776, 18.1.0.59780, 18.1_base, 18.3.0, 18.3_base, 18.4.0) or VPC versions (v18.0_base, v19.0_base, v20.0_base).
  3. Verify SSH or SFTP access is enabled
    Run 'show configuration | include ssh' or 'show management-server' to check if SSH or SFTP services are configured and active on the device.
    Affected if SSH or SFTP access is enabled and the device is running an affected version.
  4. Review active user accounts with SSH/SFTP access
    Execute 'show user account' or 'show admin users' to list accounts that have SSH or SFTP login capability.
    Affected if Any non-root user account exists with SSH or SFTP credentials on an affected version.

The environment is affected if the device runs StarOS on an ASR 5000/5500/5700 Series or Virtualized Packet Core with a version matching the listed vulnerable releases and has SSH or SFTP access enabled.

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

Upgrade StarOS to version 18.7.4, 19.5, or 20.2.3 (or later) for ASR devices, or to N4.2.7/N4.7 (or later) for VPC instances. Limit SSH access to trusted management networks and enforce least-privilege user accounts until patching is complete.

Fix this in Asr 5000 Series Software Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
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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-2017-3819 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
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