dbcve.org
Ios XrOperating system · Cisco

CVE-2016-1426

HIGH · 7.5 CVSS v3.0 Published 2016-07-15
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
Cisco IOS XR 5.x through 5.2.5 on NCS 6000 devices allows remote attackers to cause a denial of service (timer consumption and Route Processor reload) via crafted SSH traffic, aka Bug ID CSCux76819.

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

Cisco IOS XR versions 5.x through 5.2.5 on NCS 6000 series devices contains a vulnerability in the SSH handling subsystem where specially crafted SSH packets trigger excessive timer consumption, causing the Route Processor to reload and resulting in a denial of service condition.

MitigationUpgrade Cisco IOS XR to a version beyond 5.2.5 (or apply the relevant patch). As a compensating control, restrict or filter SSH access to trusted sources at network perimeter devices.

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
Ios XrOperating system
Affected:= 5.0.0= 5.0.1= 5.0_base= 5.1.0= 5.1.1= 5.1.1.k9sec= 5.1.2= 5.1.3= 5.2.0= 5.2.1= 5.2.2= 5.2.3

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 device model
    Run 'show platform' or check hardware inventory to confirm the device is a Cisco NCS 6000 series router
    Affected if Device model is NCS-6000 series or NCS 6001/6008/6010
  2. Check IOS XR version
    Run 'show version' to display the installed Cisco IOS XR version
    Affected if Version is 5.0.0, 5.0.1, 5.0_base, 5.1.0, 5.1.1, 5.1.1.k9sec, 5.1.2, 5.1.3, 5.2.0, 5.2.1, 5.2.2, or 5.2.3 (versions 5.x through 5.2.5 are affected)
  3. Verify SSH service is enabled
    Run 'show ssh' or 'show running-config | include ssh' to check if SSH is configured and active
    Affected if SSH server or client is enabled on the device
  4. Assess SSH network exposure
    Review access control lists, interface configurations, or management network placement to determine if SSH is reachable from untrusted networks
    Affected if SSH management interface is accessible from outside trusted network segments

Device is affected if it is an NCS 6000 series running Cisco IOS XR versions 5.0.0 through 5.2.5 with SSH service enabled and exposed to potentially untrusted SSH sources.

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 Cisco IOS XR to a version beyond 5.2.5 (or apply the relevant patch). As a compensating control, restrict or filter SSH access to trusted sources at network perimeter devices.

Fix this in Ios Xr Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get help mitigating

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 locally
dbcve dependency scanner

Check whether your project pulls in CVE-2016-1426 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2016-1426 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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