iOSOperating system · Cisco
CVE-2012-1311
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 · uneditedThe RSVP feature in Cisco IOS 15.0 and 15.1 and IOS XE 3.2.xS through 3.4.xS before 3.4.2S, when a VRF interface is configured, allows remote attackers to cause a denial of service (interface queue wedge and service outage) via crafted RSVP packets, aka Bug ID CSCts80643.
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 confidenceA vulnerability exists in the RSVP (Resource Reservation Protocol) implementation in Cisco IOS 15.0/15.1 and IOS XE 3.2.xS through 3.4.xS before 3.4.2S. When a VRF (Virtual Routing and Forwarding) interface is configured, specially crafted RSVP packets sent by remote attackers can cause the interface queue to wedge, resulting in a denial of service and service outage.
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
iOSOperating system
= 15.0= 15.1
Ios XeOperating system
= 3.2.0s= 3.2.1s= 3.2.2s= 3.3.0s= 3.4.0sCVSS 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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Check Cisco IOS/IOS XE versionRun 'show version' command and look for the IOS version number in the output. Compare it against the affected versions: 15.0, 15.1 for IOS, or 3.2.0S-3.4.0S for IOS XE.Affected if The device runs any version from 15.0 to 15.1 for IOS, or 3.2.0S to 3.4.0S for IOS XE (versions prior to 3.4.2S).
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Verify VRF configuration existsRun 'show vrf' or 'show ip vrf' command to list all VRF instances configured on the device.Affected if Any VRF instances are configured on the device.
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Check if RSVP is enabled on VRF interfacesRun 'show rsvp interface' or 'show ip rsvp interface' to display RSVP-enabled interfaces. Cross-reference with VRF interfaces using 'show vrf interface'.Affected if RSVP is enabled on any interface that belongs to a VRF instance.
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Inspect RSVP configuration in running configRun 'show running-config | include rsvp' and 'show running-config | include vrf' to review RSVP and VRF configuration lines.Affected if RSVP is configured globally or on specific interfaces while VRF interfaces exist on the device.
The device is affected if it runs a vulnerable IOS 15.0/15.1 or IOS XE 3.2.xS-3.4.xS version AND has RSVP enabled on any VRF-configured interface.
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 to Cisco IOS XE 3.4.2S or later, or disable the RSVP feature on VRF interfaces if not required. Implement ACL-based filtering for RSVP traffic at network edges as a temporary workaround until patching can be completed.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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 locallyCheck whether your project pulls in CVE-2012-1311 — 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-2012-1311 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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