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iOSOperating system · Cisco

CVE-2013-5527

MEDIUM · 5.7 CVSS v2.0 Published 2013-10-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
62/100
Remediation priority · Elevated
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
The OSPF functionality in Cisco IOS and IOS XE allows remote attackers to cause a denial of service (device reload) via crafted options in an LSA type 11 packet, aka Bug ID CSCui21030.

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

This vulnerability exists in the OSPF (Open Shortest Path First) routing protocol implementation in Cisco IOS and IOS XE. Attackers send specially crafted packets containing malformed options in Link State Advertisement (LSA) type 11, which causes the affected device to reload, resulting in denial of service.

MitigationApply the appropriate Cisco IOS/IOS XE software update for your platform from the Cisco security advisory. If immediate patching is not possible, consider network segmentation or access controls to limit OSPF packet exposure to trusted sources.

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
Affected:all versions
Ios XeOperating system
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
Adjacent
Complexity
M
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete

AV:A/AC:M/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. Verify if OSPF is enabled on the device
    Run 'show ip ospf' or 'show ip protocols' to check for active OSPF processes
    Affected if Any OSPF process is listed as running indicates the device could be affected by this vulnerability
  2. Confirm OSPF interfaces are actively participating in OSPF
    Run 'show ip ospf interface brief' to list interfaces with OSPF enabled
    Affected if Interfaces showing OSPF adjacency or neighbor participation are vulnerable to malformed LSA packets
  3. Check the Cisco IOS or IOS XE version
    Run 'show version' to display the software version
    Affected if All Cisco IOS and IOS XE versions are affected when OSPF is enabled; compare your version to the Cisco advisory for available patches
  4. Identify OSPF network exposure
    Review OSPF interface configurations with 'show running-config | include ospf' or 'show ip ospf interface' to determine which interfaces accept OSPF neighbors
    Affected if Interfaces with OSPF enabled and accessible to untrusted networks are at risk of receiving malformed LSA type 11 packets
  5. Check for existing OSPF neighbors
    Run 'show ip ospf neighbor' to see established OSPF adjacencies
    Affected if Active OSPF neighbors indicate the routing protocol is processing OSPF packets that could include malicious malformed LSAs

The device is affected if OSPF is enabled and running on any interface, regardless of version, since all Cisco IOS and IOS XE versions contain the vulnerability.

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 appropriate Cisco IOS/IOS XE software update for your platform from the Cisco security advisory. If immediate patching is not possible, consider network segmentation or access controls to limit OSPF packet exposure to trusted sources.

Fix this in iOS Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,820
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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-2013-5527 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