dbcve.org
Ios XrOperating system · Cisco

CVE-2011-2549

HIGH · 7.8 CVSS v2.0 Published 2011-07-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
87/100
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
Unspecified vulnerability in Cisco IOS XR 4.1.x before 4.1.1 on Cisco Aggregation Services Routers (ASR) 9000 series devices allows remote attackers to cause a denial of service (line-card reload) via an IPv4 packet, aka Bug ID CSCtr26695.

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

Unspecified vulnerability in Cisco IOS XR 4.1.x before 4.1.1 on ASR 9000 series routers allows remote attackers to cause denial of service via specially crafted IPv4 packets, triggering line-card reload.

MitigationUpgrade Cisco IOS XR to version 4.1.1 or later to remediate. Until upgraded, consider filtering or rate-limiting untrusted IPv4 traffic as a temporary mitigation.

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:= 4.1.0
Asr 9006 RouterHardware / appliance
Affected:all versions
Asr 9010 RouterHardware / appliance
Affected:all versions

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
Complete

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

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 inventory' or 'show platform' command on the router to confirm the hardware is a Cisco ASR 9006 or ASR 9010 series router
    Affected if The router model is ASR 9006 or ASR 9010
  2. Check IOS XR version
    Run 'show version' command to display the installed Cisco IOS XR software version
    Affected if The IOS XR version is 4.1.0, or any version in the 4.1.x line before 4.1.1 (such as 4.1.0, 4.1.0.1, 4.1.0.2, etc.)
  3. Verify IPv4 input feature is enabled
    Run 'show ipv4 traffic' or 'show running-config | include ipv4' to check if IPv4 packet processing is active on the router
    Affected if IPv4 is enabled and the router is processing IPv4 traffic

You are affected if the router is an ASR 9006 or ASR 9010 running any Cisco IOS XR version 4.1.0 through 4.1.0.x (i.e., any version before 4.1.1 in the 4.1.x branch) and IPv4 is enabled on the line cards.

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 version 4.1.1 or later to remediate. Until upgraded, consider filtering or rate-limiting untrusted IPv4 traffic as a temporary mitigation.

Fix this in Ios Xr 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
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2011-2549 — 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-2011-2549 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