dbcve.org
Ios XeOperating system · Cisco

CVE-2015-4291

HIGH · 7.8 CVSS v2.0 Published 2015-08-01
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
Cisco IOS XE 2.x before 2.4.3 and 2.5.x before 2.5.1 on ASR 1000 devices allows remote attackers to cause a denial of service (Embedded Services Processor crash) via a crafted series of fragmented (1) IPv4 or (2) IPv6 packets, aka Bug ID CSCtd72617.

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 Cisco IOS XE versions 2.x before 2.4.3 and 2.5.x before 2.5.1 on ASR 1000 devices allows remote attackers to cause a denial of service by crashing the Embedded Services Processor (ESP) through a crafted series of fragmented IPv4 or IPv6 packets.

MitigationUpgrade Cisco IOS XE to version 2.4.3 or later (for 2.x branch) or version 2.5.1 or later (for 2.5.x branch) on affected ASR 1000 devices. Consider implementing firewall or IPS filters to block malformed fragmented packets as an interim measure.

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 XeOperating system
Affected:= 2.1.0= 2.1.1= 2.1.2= 2.2.1= 2.2.2= 2.2.3= 2.3.0= 2.3.0t= 2.3.1t= 2.3.2= 2.4.0= 2.4.1

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 device model
    Run 'show version' or 'show inventory' to confirm the hardware is a Cisco ASR 1000 series router
    Affected if Device is not an ASR 1000 series (the vulnerability only affects ASR 1000 appliances)
  2. Determine IOS XE version
    Run 'show version' and locate the 'IOS XE Software' or 'Cisco IOS Software' version string displayed in the output
    Affected if Unable to determine the IOS XE version from command output
  3. Compare version to affected ranges
    Compare your installed IOS XE version against the vulnerable ranges: 2.1.0 through 2.4.1 (any 2.x version before 2.4.3), or 2.5.x versions before 2.5.1
    Affected if Version is 2.1.0, 2.1.1, 2.1.2, 2.2.1, 2.2.2, 2.2.3, 2.3.0, 2.3.0t, 2.3.1t, 2.3.2, 2.4.0, 2.4.1, or any 2.5.x version before 2.5.1
  4. Verify ESP processor status
    Run 'show platform' or 'show esp status' to confirm the Embedded Services Processor (ESP) is active and running
    Affected if ESP is present and operational (the denial of service crashes the ESP, so an active ESP is required to be affected)

You are affected if your ASR 1000 device runs Cisco IOS XE version 2.1.0 through 2.4.1, or 2.5.x before 2.5.1, and the ESP processor is active.

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 XE to version 2.4.3 or later (for 2.x branch) or version 2.5.1 or later (for 2.5.x branch) on affected ASR 1000 devices. Consider implementing firewall or IPS filters to block malformed fragmented packets as an interim measure.

Fix this in Ios Xe Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,330
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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-2015-4291 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