Ios XeOperating system · Cisco
CVE-2015-6273
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 · uneditedCisco IOS XE before 3.1.2S on ASR 1000 devices mishandles the automatic setup of Virtual Fragment Reassembly (VFR) by certain firewall and NAT components, which allows remote attackers to cause a denial of service (Embedded Services Processor crash) via crafted IP packets, aka Bug IDs CSCtf87624, CSCte93229, CSCtd19103, and CSCti63623.
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 confidenceCisco IOS XE before version 3.1.2S on ASR 1000 devices contains a flaw in the automatic Virtual Fragment Reassembly (VFR) setup triggered by firewall and NAT components. When certain firewall or NAT features attempt to initialize VFR, they can cause the Embedded Services Processor (ESP) to crash upon processing specifically crafted IP packets, resulting in denial of service.
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
= 2.2.1= 2.2.2= 2.2.3= 3.1.0s= 3.1.1sCVSS 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 checksWork through these to decide whether this CVE applies to you.
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Identify device modelRun 'show version' or 'show platform' to confirm the device is a Cisco ASR 1000 series routerAffected if Device is not an ASR 1000 series, then not affected by this specific vulnerability
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Check IOS XE versionRun 'show version' and locate the 'IOS XE' or 'Version' line in the output. Compare the version number against the affected list: 2.2.1, 2.2.2, 2.2.3, 3.1.0s, 3.1.1sAffected if IOS XE version is one of the affected versions listed, or is earlier than 3.1.2S on the ASR 1000 platform
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Verify firewall feature is enabledRun 'show running-config | include ip inspect' or check for firewall policies via 'show service-inspection'Affected if Firewall inspection (ip inspect) or Zone-Based Policy Firewall is configured and active
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Verify NAT is enabledRun 'show ip nat translations' or 'show running-config | include ip nat' to check for NAT configurationAffected if NAT is configured and active on the device
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Check VFR statusRun 'show vfr' or 'show vfr detail' to see if Virtual Fragment Reassembly is enabled or auto-initializedAffected if VFR is enabled or automatically created by firewall/NAT features
Device is affected if it is an ASR 1000 running Cisco IOS XE version 2.2.1-3.1.1s with firewall or NAT features enabled that trigger VFR initialization.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade Cisco IOS XE to version 3.1.2S or later on affected ASR 1000 devices. Prior to upgrade, verify firewall/NAT configurations and schedule maintenance window to minimize operational impact.
Fix this in Ios Xe
Scoped from the published advisory
- Consultation6.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,448.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2015-6273 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2015-6273 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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