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Ios XrOperating system · Cisco

CVE-2006-1927

MEDIUM · 5.0 CVSS v2.0 Published 2006-04-20
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
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, when configured for Multi Protocol Label Switching (MPLS) and running on Cisco CRS-1 or Cisco 12000 series routers, allows remote attackers to cause a denial of service (Line card crash) via certain MPLS packets, as identified by Cisco bug ID CSCsc77475.

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

Cisco IOS XR when configured for MPLS on CRS-1 or Cisco 12000 series routers contains a vulnerability where certain crafted MPLS packets can cause a line card crash, resulting in denial of service. The vulnerability is triggered by specific MPLS packet types that the affected IOS XR versions do not properly handle.

MitigationApply the Cisco fix for bug ID CSCsc77475, which typically involves upgrading IOS XR to a patched version. As an interim measure, consider filtering or rate-limiting unknown MPLS traffic at network boundaries until the patch can be deployed.

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:= 3.0.1= 3.1.0= 3.2= 3.2.1= 3.2.2= 3.2.3= 3.2.4= 3.2.50

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
Partial

AV:N/AC:L/Au:N/C:N/I:N/A:P

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 router model
    Run 'show platform' or check hardware inventory to confirm the device is a Cisco CRS-1 or Cisco 12000 series router
    Affected if Device is not CRS-1 or 12000 series (vulnerability does not apply)
  2. Check IOS XR version
    Run 'show version' or 'admin show version' to retrieve the installed IOS XR version
    Affected if Version matches 3.0.1, 3.1.0, 3.2, 3.2.1, 3.2.2, 3.2.3, 3.2.4, or 3.2.50
  3. Verify MPLS is enabled
    Run 'show mpls interfaces' or 'show running-config | include mpls' to check if MPLS is configured on any interfaces
    Affected if MPLS is enabled on the router (required for the vulnerability to be triggerable)
  4. Confirm line card presence
    Run 'show platform' or 'admin show inventory' to verify line cards are present
    Affected if Line cards exist (the vulnerability causes line card crash, so line cards must be present for impact)

You are affected if you have a CRS-1 or 12000 series router running IOS XR version 3.0.1, 3.1.0, 3.2, 3.2.1, 3.2.2, 3.2.3, 3.2.4, or 3.2.50 with MPLS 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

Apply the Cisco fix for bug ID CSCsc77475, which typically involves upgrading IOS XR to a patched version. As an interim measure, consider filtering or rate-limiting unknown MPLS traffic at network boundaries until the patch can be deployed.

Fix this in Ios Xr 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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Scan for this in your stack

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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-2006-1927 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